IC-NRLF 


U  F 


Mechanical  Maneuvers 


PREPARED  BY 

THE  DEPARTMENT  OF  ARTILLERY, 
COAST  ARTILLERY  SCHOOL 


PUBLISHED  BY 
THE  COAST  ARTILLERY  JOURNAL 


PRINTING  PLANT,  COAST  ARTILLERY  SCHOOI 
FORT  MONROE,  VIRGINIA 

AUGUST,  1922 
1C.  A.  SCHOOL.  8-14-22-5000. 


Mechanical  Maneuvers 


Mechanical  maneuvers  are  the  application  of  machines  and 
of  mechanical  power  for  mounting,  dismounting,  moving,  and 
transporting  artillery. 

It  is  of  the,  utmost  importance  that  officers  and  enlisted  men 
designated  to  execute  work  of  this  nature  have  a  knowledge  of : 

1.  The  machines,  appliances  and  tools  required. 

2.  How  to  improvise  material. 

3.  The  breaking  strength  and  safe  load  of  the  material  used. 

4.  How  to  obtain  the  greatest  advantage  from  the  power  ap- 

plied. 

5.  The  safest  and  speediest  method  to  be  used. 

The  machines  and  appliances  usually  employed  for  moving 
heavy  artillery  are : 

Rope,  blocks  and  tackle  Sling  carts 

Handspikes  (Levers)  Tractors 

Hydraulic  Jacks  E.  R.  Trucks 

Gins  Push  carts 

Shears  Mauls 

Derricks  Sledge  Hammer 
Blocks,  skids,  wayplanks  and         Hatchet 

Rollers  Axe 

Collars  Hand  saw 

Chocks  Crosscut  saw 

Cradles  Nails 
Capstans,  crab  or  drum 

There  is  a  wrong  way  and  a  right  way  to  do  everything. 
There  is  no  condition  when  the  wrong  way  is  more  fraught  with 
the  possibilities  of  disaster  than  in  the  handling  of  heavy  weights 
or  vehicles  with  improvised  tackle.  There  may  be  a  time  when 
the  tackle  that  jams  or  the  knot  that  refuses  to  be  freed,  may  be 
as  dangerous  to  life  or  equipment  as  the  tackle  that  breaks  or 
the  hitch  that  slips.  It  is  very  easy  to  master  the  simple  nomen- 
clature of  the  rigger,  and  it  is  equally  simple  to  learn  the  few 
knots,  splices,  hitches,  and  riggings  necessary  to  meet  any  situation 
that  may  arise  in  the  Coast  Defenses  or  in  the  field. 

(i) 


2  MECHANICAL  MANEUVERS 

CORDAGE 

A  Yarn  is  a  thread  formed  by  twisting  several  fibres  together, 
hemp  or  other  fibrous  material.  The  common  fibres  are:  Manila, 
Hemp,  Jute,  and  Sisal.  Manila  fibre  is  best  for  ordinary  use  and 
rope  made  of  it  should  always  be  used  if  possible.  Hemp  is 
stronger  but  not  so  flexible  and  deteriorates  more  rapidly  from 
moisture. 

A  Strand  is  a  number  of  these  yarns  twisted  or  spun  to- 
gether ;  three  or  four  strands  form  a  rope  if,  after  they  are  twisted 
together,  they  measure  at  least  one  inch  or  more  in  circumference. 

Wire  Rope  contains  a  number  of  wires  twisted  into  strands, 
three  or  six  of  which  are  laid  up  around  a  wire  or  hemp  core.  Wire 
rope  is  abiut  six  times  as  strong  as  hemp  rope  but  lacks  elasticity 
and  is  difficult  to  handle.  Inasmuch  as  it  is  used  principally  for 
permanent  rigging  and  not  adapted  for  field  work,  it  will  not  be 
further  considered  here. 

Ropes  are  ordinarily  composed  of  three  strands  laid  up  right 
handed,  so  that  when  a  strand  is  followed  away  from  the  observer 
the  rotation  will  be  clock-wise,  or  laid  up  with  the  sun.  This 
is  known  as  Hawser-Laid,  Plain  Laid,  or  Right  Handed  Rope. 
Hawser  is  also  a  term  applied  to  larger  rope. 

Shroud  Laid  Rope  contains  four  strands  usually  laid  right 
handed  around  a  smaller  rope  called  a  Heart  or  Core. 

Spun  Yarn  is  made  by  twisting  together,  very  loosely,  two  or 
more  well  tarred  Yarns,  and  is  also  designated  by  numbers  of 
yarns,  as  two  yarn,  three  yarn,  etc.  It  is  used  for  Serving,  Seizing. 
Stops,  Mousing,  etc. 

Marline  is  also  made  of  tarred  yarn,  but  it  is  tightly  twisted 
and  much  harder  and  smoother  than  spun-yarn.  It  is  not  fit  for 
serving,  when  the  rope  served  is  to  be  bent  up,  as  it  is  not  pliable 
enough  to  cover  the  rope  in  s,uch  cases. 

The  Jaws  of  a  rope  are  the  spaces  between  the  strands.  A  rope 
is  Long  Jawed  or  Short  Jawed  as  it  is  loosely  or  tightty  laid  up. 

The  Lay  of  a  rope  is  the  direction  of  twist  of  the  strand  of  the 
rope,  it  is  opposite  to  the  twist  of  yarns  in  the  strands.  This 
causes  the  rope  to  lay  together  when  put  under  a  strain,  and  the 
Yarns  and  Strands  to  bind  together  against  each  other  in  all 
directions. 

The  Standing  Part  is  the  principal  portion  or  longest  part  of 
the  rope. 

The  End  is  the  free  end  used  in  forming  a  knot  or  hitch. 


MECHANICAL    MANEUVERS  O 

The  Bight  of  a  rope  is  any  part  not  an  end.  For  example  a 
Bight  is  a  loop  formed  by  binding  or  doubling  the  rope. 

To  Whip  a  rope  is  to  bind  its  end  with  a  bit  of  yarn  or  twine 
to  prevent  its  unraveling. 

A  rope  is  Seized  when  two  parts  of  it  are  bound  together  by 
spun  yarn,  marline  or  cord.  Round  Seizing  is  when  the  seizing 
material  is  wound  round  both  ropes  without  passing  between  them, 
while  in  Racking  Seizing  the  seizing  material  is  wound  round  the 
rope  in  figures  of  eight. 

Pointing  is  the  operation  of  tapering  the  end  of  a  rope  so  that 
it  will  enter  a  hole  or  block  more  easily. 

F rapping  is  several  turns  about  two  or  more  ropes  to  bind  them, 
as  about  lashing,  or  to  draw  two  ropes  and  hold  them  while  taking 
in  slack. 

Lashing  is  the  binding  or  making  fast  of  one  object  to  another 
by  means  of  ropes. 

A  Strap  or  Sling  is  usually  made  of  rope,  the  ends  of  which 
are  either  spliced  or  tied  together;  it  is  passed  round  the  object 
to  be  moved,  the  hook  of  the  tackle  being  passed  through  both 
bights,  or  through  one  bight  after  it  has  been  passed  through  the 
other  one. 

Mousing  a  hook  is  to  place  seizing  about  the  point  and  back  of 
the  hook  to  strengthen  it,  and  to  prevent  it  from  disengaging  itself. 

Worming  a  rope  is  filling  up  the  jaws  by  passing  spun  yarn 
along  them,  to  render  the  surface  smooth  for  parceling  and  serving. 

Parceling  a  rope  is  wrapping  narrow  strips  of  canvas  about  it, 
well  tarred  in  order  to  secure  it  from  being  injured  by  water.  The 
parceling,  is  put  on  with  the  lay  of  the  rope.  Its  use  is  to  prevent 
chafing  or  cutting  of  a  rope  when  a  strain  is  brought  against  a 
rough  surface  or  sharp  edge.  For  this  purpose  old  rope  or  canvas 
wound  around  is  sufficient. 

Serving  is  the  laying  on  of  spun  yarn  or  other  small  material 
in  turns  round  the  rope,  close  together,  and  hove  taut  by  use  of  a 
serving  board  for  small  rope  and  serving  mallet  for  large  rope. 
Small  ropes  are  sometimes  served  without  being  wormed,  as  the 
crevices  between  the  strands  are  not  large  enough  to  make  the 
surface  very  uneven;  but  a  large  rope  is  always  wormed  and  par- 
celed, before  being  served.  The  service  is  put  on  against  the  lay  of 
the  rope. 

Cable-Laid  rope  is  composed  of  nine  (9)  strands,  and  is  made 
by  first  laying  up  three  ropes  of  three  strands  each,  with  the  sun, 
and  then  laying  the  three  ropes  up  together  into  one,  against 
the  sun. 


4  MECHANICAL    MANEUVERS 

Right -Hand  rope  must  be  coiled  with  the  sun,  and  Cable-Laid 
rope  against  the  sun. 

The  fibers  of  Hemp  rope  are  obtained  from  the  Hemp  Plant, 
those  of  Manila  Rope  from  a  species  of  Plantain.  Hemp  Rope  is 
about  one-third  stronger  than  Manila. 

The  size  of  rope  is  always  given  in  inches  and  fractions,  anl  is 
measured,  on  the  circumference,  for  the  reason  that  it  is  seldom 
possible  to  get  a  squarely  cut  end  in  order  to  measure  the  diameter. 
In  making  requisitions  for  rope,  it  should  be  clearly  indicated  that 
this  measure  is  the  one  considered. 

Preservation  in  Store.  Ropes  should  be  placed  in  the  upper 
stories  of  buildings,  coiled  up  and  labeled;  large  ropes  on  skids, 
allowing  free  circulation  of  air;  small  ropes  hung  up  to  the  joists 
on  pins  or  hooks.  Ropes  should  not  be  coiled  until  perfectly  dry; 
they  should  be  uncoiled  every  year,  and  stretched  out  for  several 
days  in  the  dry  season.  Ropes  long  in  store  lose  their  strength. 

A  safe  general  rule  for  calculating,  roughly  the  strength  of  all 
ropes  is  as  follows:  one  fourth  the  square  of  the  circumference 
gives  the  breaking  weight  in  tons  of  2000  pounds.  Due  allowance 
must  be  made  for  loss  of  strength  by  wear  and  tear. 

When  using  tackles,  multiply  the  weight  thus  found  by  one- 
half  the  number  of  sheaves  in  the  blocks. 

Old  rope  should  be  carefully  examined  before  attempting  to 
work  with  it.  A  few  months  exposure  weakens  a  rope  20  to  50 
per  cent.  Dry  rot  will  sometimes  make  a  rope  almost  useless 
without  changing  its  external  appearance  to  any  extent.  Rope 
will  sometimes  chafe  to  powder  in  the  center,  due  to  friction  be- 
tween the  strands  and  yarns  while  being  bent  'Over  the  sheaves 
of  blocks.  A  rope  is  slightly  weakened  by  tarring  and  wetting. 
Dry  ropes  shorten  quite  perceptibly  upon  being  wet  and  for  this 
reason  it  is  never  safe  to  leave  a  tension  on  rigging  when  it  is 
liable  to  be  wet,  if  an  increase  on  that  tension  will  cause  damage. 

Rope  should  always  be  stopped  up,  either  with  the  ends  or 
with  the  rope-yarn  stops,  to  prevent  it  getting  into  a  snarl.  When 
using  ropes  for  hauling,  they  should  never  be  dragged  upon  the 
ground. 

To  stop  up  a  coil  of  rope  with  the  end.  Lay  off  two  or  three 
turns  of  the  coil  and  take  a  clove  hitch  around  all  parts  of  one 
side  of  the  coil.  Do  the  same  on  the  other  side.  If  the  rope 
should  be  rove  in  ;i  l;i<-klc,  run  it  "two  blocks"  and  make  a  hitch 
around  the  fall  between  the  blocks. 


MECHANICAL  MANEUVERS  5 

KNOTS  AND  SPLICES 

The  principle  of  the  knot  is  that  no  two  parts  which  would 
move  in  the  same  direction,  if  the  knot  were  to  slip,  should  lie 
along  side  or  touching  one  another. 

The  Square  Knot  and  Thief  Knot  are  excellent  illustrations  of 
this  principle. 

Square  Knot.  Take  an  over-hand  knot  around  a  spar;  take  an 
end  in  each  hand  and  cross  them  on  the  same  side  of  the  standing 
part  on  which  they  come  up,  pass  one  end  around  the  other,  and 
bring  it  up  through  the  bight.  This  is  sometimes  called  a  Reef 
Knot.  If  the  ends  are  crossed  the  wrong  way,  sailors  call  it  a 
Granny  Knot.  If  the  ends  come  out  on  opposite  sides  it  is  a 
Thief  Knot. 

Single  Becket  or  Sheet  Bend  (Weaver's  Knot).  Pass  the  end 
of  a  rope  up  thru  the  bight  of  another,  round  both  parts  of  the 
other,  and  under  its  own  part.  This  does  not  jam  and  is  useful 
in  tying  two  ropes  together. 

Double  Becket.  Same  as  single  becket  except  two  turns  are 
taken  round  both  parts  before  passing  under  its  own  part.  Used 
to  tie  ropes  of  different  sizes  together.  The  bight  should  be  taken 
in  the  larger  ropes. 

Two  Half  Hitches.  Pass  the  end  of  the  rope  around  the  stand- 
ing part  and  bring  it  up  thru  the  Bight.  This  is  a  half  hitch. 
Take  it  around  again  in  the  same  manner  for  two  half  hitches. 

Round  Turn  and  Two  Half  Hitches.  Take  a  round  turn 
around  a  stake  or  post,  and  secure  the  end  by  two  half  hitches 
around  the  standing  part.  This  is  very  useful  in  securing  guys  to 
the  stakes. 

Fisherman's  Bend  (Anchor  Knot).  Take  two  turns  around 
the  spar  with  the  end  of  the  rope;  hitch  the  end  around  the 
standing  part  and  thru  both  turns,  and  then  pass  the  end  over 
the  second  and  under  the  first  turn.  This  knot  will  not  jam 
when  wet. 

A  Timber  Hitch.  Take  the  end  of  a  rope  around  the  spar, 
lead  it  under  and  over  the  standing  part,  and  pass  two  or  more 
turns  around  its  own  part ;  pass  the  first  turn  over  the  end  part 
instead  of  thru  the  bight,  as  in  the  half  hitch.  Used  in  temporarily 
securing  the  ends  of  ropes  to  spars. 

A  Clove  Hitch  is  made  by  passing  the  end  of  a  rope  round  a 
spar,  over,  and  bringing  it  under  and  round  behind  its  standing 
part,  over  the  spar  again  and  up  thru  its  own  part.  It  may  then, 


b  MECHANICAL    MANEUVERS 

if  necessary,  be  stopped  or  hitched  to  its  own  part,  the  only  dif- 
ference between  two  half  hitches  and  a  clove  hitch  being  that 
one  is  hitched  round  its  own  standing  part  and  the  other  is  hitched 
round  a  spar  or  another  rope. 

A  Rolling  Hitch.  Pass  the  end  of  a  rope  round  a  spar;  take 
it  round  the  second  time,  nearer  to  the  standing  part;  then  carry 
it  across  the  standing  part,  over  and  round  the  spar  and  up  thru, 
the  bight.  A  strap  or  tail  block  is  fastened  to  a  rope  by  this  hitch. 
Used  in  shifting  the  fall  from  one  end  of  the  windlass  to  the  other. 
(See  Nipper  and  screw). 

A  Blackwall  Hitch.  Form  a  bight  by  putting  the  end  of  a 
rope  across  and  under  the  standing  part;  put  the  hook  of  a  tackle 
thru  it,  the  center  of  the  bight  resting  against  the  back  of  the 
hook,  and  the  end  jammed  in  the  bight  of  the  hook  by  the  standing 
part  of  the  rope. 

A  Cat's  Paw.  Make  a  large,  bight  in  a  rope,  and  spread  it 
open,  putting  one  hand  at  one  part  of  the  bight  and  the  other 
at  the  other,  and  letting  the  standing  part  and  end  come  together, 
turn  the  bight  over  from  you  three  times,  and  a  small  bight  will  be 
formed  in  each  hand,  bring  the  two  small  bights  together,  and 
put  the  hook  of  the  tackle  thru  them  both.  This  is  very  useful  in 
applying  a  purchase  or  tackle  to  the  fall  of  another. 

A  Sheep  Shank.  Make  two  long  bights  in  a  rope  which  shall 
overlay  one  another,  take  a  half  hitch  over  the  end  of  each  bight 
with  the  standing  part  which  is  next  to  it.  Used  to  shorten  rope, 
or  cut  out  a  weak  part,  temporarily. 

A  Bowline  Knot.  Take  the  end  of  a  rope  in  your  right  hand 
and  the  standing  part  in  your  left ;  lay  the  end  over  the  standing 
part,  and  with  the  left  hand  make  a  bight  of  the  standing  part 
over  it;  take  the  end  under  the  lower  standing  part  up  over  the 
cross,  and  down  thru  the  bight.  This  is  very  useful  in  forming 
a  temporary  eye  at  the  end  of  a  rope. 

Bowline  on  a  Bight.  The  first  part  is  made  like  the  above 
bowline,  with  the  double  part  of  a  rope,  then  the  bight  is  pulled 
thru  sufficiently  to  allow  it  to  be  bent  past  and  come  up  in  the 
position  shown.  It  makes  a  comfortable  sling  for  a  man,  more  so 
than  a  single  bight,  as  the  bights  may  be  adjusted  to  an  equal 
length. 

Running  Bowline.  This  is  simply  a  bowline  with  a  bight 
enclosing  the  standing  part. 

A  Marlinespike  Hitch.  Lay  the  marlinespike  upon  the  seizing 
stuff,  and  bring  the  end  over  the  standing  part  so  as  to  form  a 
bight,  lay  this  bight  back  over  the  standing  part,  putting  the 


MECHANICAL    MANEUVERS  7 

marlinspike  down  thru  the  bight,  under  the  standing  part,  and  up 
thru  the  bight  again.    Very  useful  in  putting  on  lashings,  etc. 

Carrick  Bend.  Form  a  bight  on  a  rope  and  lay  the  end  across 
the  standing  part;  stick  the  bight  of  another  rope  up  thru  the 
loop  thus  formed,  and  carry  the  end  of  the  first  rope,  under  the 
standing  part,  and  thru  the  loop  formed  by  its  bight,  stop  each 
end  to  its  own  standing  part. 

Splicing  is  putting  the  end  of  ropes  together  by  opening  the 
strands  and  placing  them  into  one  another,  or  by  putting  the 
strands  of  the  end  of  a  rope  between  those  of  the  bight. 

A  Short  Splice.  Unlay  the  strands  for  a  convenient  length, 
then  take  an  end  in  each  hand,  place  them  one  within  the  other 
and  draw  them  close.  Hold  the  end  of  one  rope  and  three  strands 
which  came  from  the  opposite  rope  fast  in  the  left  hand,  or  if  the 
rope  .be  large,  stop  them  down  to  it  with  a  rope-yarn.  Take  the 
middle  strand,  which  is  free,  pass  it  over  the  strand  which  is 
first  next  to  it,  then  thru  under  the  second  and  out  between 
the  second  and  third  from  it,  then  haul  it  taut.  Pass  each  of  the 
six  strands  in  the  same  manner;  first,  those  of  one  end  and  then 
those  of  the  other.  The  same  operation  may  be  repeated  with  each 
strand,  passing  each  over  the  third  strand  from  it,  and  under  the 
fourth,  and  thru,  or,  as  is  more  usual,  after  the  ends  have  been 
stuck  once,  untwist  each  strand,  divide  the  yarns,  pass  one-half 
as  above  described,  and  cut  off  the  other  half.  This  tapers  the 
splice. 

A  Long  Splice.  Unlay  the  ends  of  two  ropes  to  a  distance 
three  or  four  times  greater  than  for  a  short  splice,  and  place  them 
within  one  another  as  for  a  short  splice.  Unlay  one  strand  for  a 
considerable  distance  and  fill  up  the  interval  which  it  leaves  with 
the  opposite  strand  from  the  other  rope.  Twist  the  ends  of  these 
two  together,  then  do  the  same  with  two  more  strands.  The  two 
remaining  strands  are  twisted  together  in  the  place  where  they 
were  first  crossed.  Open  the  two  last  named  strands,  divide  in  two, 
take  an  overhand  knot  with  the  opposite  halves,  and  lead  the  ends 
over  the  next  strand  and  thru  the  second  as  the  whole  strands 
were  passed  for  the  short  splice.  Cut  off  the  other  two  halves.  Do 
the  same  with  the  others  that  are  placed  together,  dividing,  knot- 
ting, and  passing  them  in  the  same  manner.  Before  cutting"  off 
any  of  the  half  strands,  the  rope  should  be  brought  well  upon  a 
stretch.  Sometimes  the  whole  strands  are  knotted,  when  divided, 
and  the  half  strands  passed  as  above  described.  This  splice  does 
not  increase  the  diameter  of  the  rope  and  is  used  for  splicing  a 
fall  or  other  rope  that  runs  thru  blocks  or  pulleys. 


MECHANICAL    MANEUVERS 


USE   OF  KNOTS 


Overhand  Knot  is  used  at  the  end  of  a  rope  to  prevent  un- 
reaving  or  to  prevent  the  end  of  a  rope  from  slipping  thru  a  block. 

figure  of  Eight  is  used  for  purposes  similar  to  the  above. 

Square  or  Reef  Knot  is  used  for  joining  two  ropes  of  the  same 
size.  With  dry  rope  a  reef  knot  is  as  strong  as  the  rope ;  with 
wet  rope  it  slips  before  the  rope  breaks,  while  a  double  sheet  bend 
or  (Double  Becket)  is  bound  to  hold. 

Single  Sheet  Bend  (Single  Becket)  is  used  for  joining  ropes 
together,  especially  when  unequal  in  size.  It  is  more  secure  than 
the  Reef  Knot  but  more  difficult  to  untie.  This  is  also  known  as 
a  Weaver's  Knot. 

Double  Sheet  Bend  or  (Double  Becket)  is  used  also  for  fasten- 
ing ropes  together  of  unequal  size,  especially  wet  ones,  and  is 
more  secure  than  the  single  sheet  bend. 

Two  Half-Hitches  is  especially  useful  for  belaying  or  making 
fast  the  end  of  a  rope  around  its  own  standing  part.  The  end  may 
be  lashed  down,  or  seized,  to  the  standing  part  with  a  bit  of  spun 
yarn.  This  adds  to  its  security  and  prevents  slipping.  This  knot 
should  never  be  used  for  hoisting  a  spar. 

Round  Turn  and  Two  Half-Hitches  is  like  the  preceding,  except 
that  a  turn  is  first  taken  around  the  spar  or  post. 

Anchor  Knot  is  used  for  fastening  a  rope  to  a  ring  or  an  anchor. 

Clove  Hitch,  generally  used  for  fastening  a  rope  at  right  angles 
to  a  spar,  or  at  the  commencement  of  a  lashing.  If  the  end  of  the 
spar  is  free  the  hitch  is  made  by  first  forming  two  loops,  and  plac- 
ing the  right-handed  loop  over  the  other  one,  then  slipping  the 
loop  over  the  end  of  the  spar. 

Timber  Hitch,  is  used  for  hauling  and  lifting  spars.  It  can 
be  easily  loosed  when  the  strain  is  taken  off,  but  will  not  slip  un- 
der pull.  When  used  for  hauling  spars,  a  half-hitch  is  added 
near  the  end  of  the  spar. 

Telegraph  Hitch,  is  used  for  hoisting  or  hauling  a  spar. 

Hawser  Bend,  is  used  for  joining  two  large  cables.  Each  end 
is  seized  to  its  own  standing  part. 

Cat's  Paw.  It  gives  a  double  beai^ng  surface,  and  will  not  cut 
the  rope. 

Sheep  Shank  is  used  for  shortening  a  rope,  or  to  pass  by  a 
weak  spot,  a  half  hitch  is  taken  with  the  standing  parts  around 
the  Bights. 

Mooring  Knot.  Take  two  turns  round  the  moorings  or  snub- 
bing post;  pass  the  free  end  of  the  rope  under  the  standing  part; 


MECHANICAL    MANEUVERS 


9 


take  a  third  turn  above  the  other  end  and  pass  the  free  end  be- 
tween two  upper  turns. 

Rolling  Hitch,  used  for  hauling  a  large  rope  or  cable.  Two 
turns  are  taken  around  the  large  rope  in  the  direction  in  which  it 
is  to  be  hauled,  and  the  one-half  hitch  made  on  the  other  side  of 
the  hauling  part.  A  most  useful  knot,  and  quickly  made.  For  ar- 
mored cable  or  wet  manila  rope,  the  hitch  must  be  made  with  a 
strap  of  rope  yarn.  Rope  will  not  hold. 

Blackwall  Hitch,  is  used  for  attaching  a  single  rope  to  a  hook 
of  a  block  for  hoisting.  A  variation  is  the  Midshipman's  Hitch; 
the  end  is  brought  round  the  point  of  the  hook,  over  the  standing 
part. 

DIMENSIONS,   WEIGHT,    AND   STRENGTH   OF   MANILA  ROPE 

(Taken  from  Eng.  Field  Manual) 


Diameter 

Circum- 
ference 

Weight  in 
pounds  per 

Breaking 
Load. 

Proper  working 
Load  depending 

100  feet. 

upon  age  and 

condition. 

Inches 

Inches 

Pounds 

Pounds 

0.32 

1 

3.3 

780 

120-390 

.48 

m 

7.4 

1600 

250-800 

.64 

2 

13.2 

2730 

350-1300 

.80 

2^ 

20.6 

4300 

600-2000 

.96 

3 

29.7 

6100 

900-2800 

1.11 

3^ 

40.4 

8500 

1100-4000 

.27 

4 

52.8 

11600 

1500-5000 

.43 

4K 

66.8 

15000 

2000-6500 

.59 

5 

82.5 

18400 

2600-8000 

.75 

5^ 

99.8 

22000 

3000-10000 

.91 

6 

119 

25000 

3500-11500 

2.07 

6^ 

139 

29100 

4000-13000 

2.23 

7 

162 

32700 

4600-15000 

2.39 

iy> 

186 

36300 

5000-1  6000 

Up  to  5  inches  in  circumference  rope  is  made  in  coils  of  1200 
feet. 

BLOCKS  AND  TACKLES 

The  parts  of  a  Block  are  the  Shell,  or  Frame,  the  Sheaves  or 
wheel  upon  which  the  rope  runs,  and  the  Pin  upon  which  the 
Sheaves  turn  in  the  shell ;  and  the  sides  of  the  shell  are  the  Cheeks 
and  the  Swallaw  is  the  spare  between  the  sheave  and  the  frame 
through  which  the  rope  passes.  A  Strap  of  iron  or  yoke  is  passed 
around  the  Shell  and  forms  attachments  for  a  Hook  atone  end, 
and  an  Eye  at  the  other. 

Blocks  are  made  of  Wood,  Wood  and  Metal,  and  entirely  of 
Metal.  In  the  latter  case,  the  Strap  is  replaced  by  bolts  at  top 


10  MECHANICAL    MANEUVERS 

and  bottom,  or  the  strap  runs  through  the  Eye  of  the  Hook  and 
has  a  bolt  securing  the  two  ends  at  the  bottom  through  a  metal 
grommet. 

Blocks  are  designated  by  the  Length  of  the  Shell  in  Inches  and 
by  the  Number  of  Sheaves.  The  largest  rope  a  wooden  block  will 
take  has  a  circumference  equal  to  one-third  the  length  of  the 
shell.  Self-lubricating  blocks  may  be  obtained  and  are  to  be  pre- 
ferred. Blocks  with  one,  two,  three  or  four  sheaves  are  called 
Single,  Double,  Triple  or  Quadruple  blocks. 

A  Snatch  Block  is  a  single  block  with  a  shell  and  strap  open 
at  one  side  to  admit  a  rope  without  passing  the  end  through. 

A  Tail  Block  is  a  Single  block,  strapped  with  an  Eye  Splice, 
and  having  a  long  end  left  by  which  to  make  the  block  fast  to 
any  object. 

Wooden  blocks  should  be  kept  properly  protected  from  weather 
and  damage  from  rough  handling,  well  filled  with  paint  and 
properly  lubricated. 

Metal  blocks  should  be  painted,  oiled  and  kept  free  from  rust. 
All  blocks  should  be  watched  for  cracked  shells  or  sheaves  and 
worn  pins. 

TACKLES 

A  Tackle  is  a  combination  of  ropes  and  blocks  working  to- 
gether to  aid  in  moving  heavy  weights.  The  moving  block  is  the 
running  block,  the  fixed  block  is  the  standing  block.  From  where 
the  end  of  the  rope  is  made  fast  to  one  block  to  where  it  passes 
over  the  first  sheave  in  the  other  block,  is  called  the  Standing 
Part,  the  rope  between  the  blocks  is  the  Running  Part,  and  the 
part  to  which  the  Pull  is  applied  is  called  the  Fall. 

A  Simple  Tackle  consists  of  one  or  more  Blocks  rove  with  a 
single  rope  or  fall.  The  end  of  the  fall  fixed  in  the  Tackle  is 
called  the  Standing  End;  the  other  is  the  Running  End. 

To  Over  Haul  is  to  separate  the  Blocks,  to  Round  In  to  bring 
them  closer  together.  When  the  blocks  are  in  contact  they  are 
said  to  be  Chockablock.  • 

By  Power  of  a  tackle  is  meant  its  mechanical  advantage,  or  the 
ratio  of  the  force  exerted  by  it  to  that  applied  to  the  Fall,  or  in 
other  words,  it  is  the  Weight  Lifted  divided  by  the  Pull  on  the  Fall. 

The  actual  power  of  a  Tackle  may  be  obtained  by  first  com- 
puting the  theoretical  power. 

The  theoretical  power  of  a  tackle  is  obtained  by  assuming  that 
the  rope  is  perfectly  flexible,  not  elastic,  and  that  the  blocks  have 
no  friction.  It  is  (approximately)  equal  to  the  number  of  parts 


MECHANICAL    MANEUVERS  11 

of  the  rope  attached  to  or  running  from  either  side  of  the  movable 
block,  or  another  simple  rule  is,  the  force  applied  multiplied  by 
the  number  of  the  moving  parts  equals  the  gaining  power  of  the 
tackle. 

The  above  result  is  considerably  modified  in  practice  owing  to 
the  loss  of  power  due  to  friction  of  the  sheaves  and  stiffness  of  the 
rope.  Under  the  supposition  that  the  blocks  are  well  lubricated 
and  that  there  is  no  twist  in  the  tackle,  the  allowance  to  be  made 
for  friction  is  1/8  to  1/12  (an  average  of  about  1/10)  the  weight 
for  each  sheave  in  use,  this  of  course  depends  on  the  kinds  of 
sheaves  and  the  flexibility  of  the  rope. 

By  means  of  the  following  formula  the  actual  power  of  any 
tackle  may  be  calculated  from  the  corresponding  theoretical  power : 

p==W(m-fn) 


mf 

In   which   P  =  pull  on  the  fall  of  the  rope. 
"W  =  weight  to  be  raised. 
f  =  theoretical  power  of  the  tackle. 
n  =  number  of  sheaves. 

—  =  the  part  of  W  to  be  added  for  each  sheave  in  use. 
m 

The  following  example  will  illustrate  the  difference  between 
the  actual  power  and  the  theoretical  power  of  a  tackle  : 

EXAMPLE  1.     A  Weight  of  15,000  pounds  is  to  be  lifted  by  a 
tackle  consisting  of  two  Treble  blocks. 

Required:   (a)   The  theoretical  pull  required  to  lift  the  weight. 
(b)   The  actual  pull  required  to  lift  the  weight. 

SOLUTION:   (a)   Since  there  are  six  ropes  leading  to  or  away 
from  the  movable  block  the  theoretical  power  is  6. 
The  pull  to  be  applied  then  = 


.  =  2500  pounds  (Ans.) 
6 

W(m+n) 


mf 

W  =  15000  pounds 
m  =  10 

n=    6 

f=    6 


12 


MECHANICAL    MANEUVERS 


__  15000  X  (10  +  6)       15000  X  16  _  240000 

60 


10  X  6 


60 


4000  pounds  (Ans.) 


In  solution  (b)  it  requires  1500  pounds  more  pull  to  raise  the 
weight  than  it  would  have  had  there  been  no  friction,  as  fric- 
tion and  stiffness  of  rope,  represents  a  loss  of  about  60%  in  the 
pull. 

Whip  (Figure  1).  The  simplest  form  of  tackle;  it  is  made  by 
a  rope,  rove  through  a  single  block. 

Whip  Upon  Whip,  so  called  where  the  block  of  one  whip  is 
attached  to  the  fall  of  another. 


WHIP  TACKLE 
Figure  1 


GUN  TACKLE 
Figure  2 


LUFF  TACKLE 
Figure  3 


Gun  Tackle  (Figure  2),  is  made  by  reeving  a  rope  through  two 
single  blocks  and  making  the  standing  end  fast  to  the  upper  block. 

Luff  Tackle  (Figure  3)  is  made  by  reeving  a  rope  through  a 
single  and  double  block.  Inverted  it  is  called  a  Watch  or  Tail 
tackle. 

Luff  Upon  Luff.  A  luff  tackle  upon  the  fall  of  another  luff 
tackle  is  so  called. 

Gin  Tackle  consists  usually  of  a  double  and  a  treble  block,  but 
may  consist  of  a  single  and  a  double  block. 

Single  Burton,  consists  of  two  single  blocks. 

Double  Burton,  a  single  Burton  with  an  additional  whip  at- 
tached to  its  fall,  the  standing  part  of  which  is  also  attached  to  the 
weight  to  be  raised. 

Spanish  Burton,  a  gun  tackle  with  a  whip  attached  to  its  fall. 

Double  Spanish  Burton,  a  luff  tackle  with  a  whip  attached  to  its 
fall  in  the  same  manner  as  a  Spanish  Burton. 

When  one  tackle  is  applied  to  the  Fall  of  another  the  power 


MECHANICAL    MANEUVERS 


13 


Figure  4 


14 


MECHANICAL    MANEUVERS 


obtained  is  found  by  multiplying  their  respective  values  together. 
Example :— Luff  upon  Luff  power  equals  3  X  3  or  power  of  9. 

LEVERS 

There  are  three  Classes,  or  orders,  of  levers,  depending  upon 
the  position  of  the  fulcrum. 

1st.     (See  Figure  5.) 

Where  the  Fulcrum  f  is  between  the  weight  W  and  the  point  of 
application  of  force  P. 


Figure  5 

2nd.     (See  Figure  6.) 
Where  W  is  between  f  and  P. 


Figure  6 

3rd.     (See  Figure  7.) 
Where  P  is  between  f  and  W. 


Figure  7 

The  distance  from  the  point  of  application  of  the  force  to  the 
Fulcrum  is  called  the  Lever  Arm  L,  and  from  the  weight  to  the 
Fulcrum  the  Counter  Lever  Arm  Cl.  This  is  on  the  supposition 
that  the  Lever  is  straight  and  that  W  and  P  act  at  right  angles  to 
it.  Suppose  now  we  have  levers  of  the  shape  shown  in  Figures 


MECHANICAL    MANEUVERS 


15 


Figure  8 


Figure  9 


4J4J 


Figure  10 


47 1-4- 


Figure  11 


16 


MECHANICAL    MANEUVERS 


8,  9,  and  10,  then  L  and  Cl  are  the  perpendicular  distances  from 
f  to  the  lines  of  application  of  P  and  W,  where  af  is  the  counter 
Lever  Arm  and  bf  the  lever  Arm. 

Lever  of  the  first  class 

Example:    Use  of  handspike  as  a  pry. 

Lever  of  the  second  class 

Example :     Operating  lever  on  hydraulic  jack. 

Example :    The  hoist  arm  on  a  crane  or  derrick. 

In  each  of  these  classes  the  distance  from  the  point  of  appli- 
cation of  the  force  to  the  fulcrum  is  called  the  lever  arm  (L)  and 
from  the  weight  to  the  fulcrum  the  counter  lever  arm  ( Cl ) . 

Double  Compound  Lever — The  mechanical  advantage  of  this 

T         T  ' 
lever  is  _  V  _.  in  which  L  and  L'    Cl  and  Cl'  pertain  to  the  cor- 

Cl      Cl' 
responding  parts  of  the  two  levers.     The  power  of  a  treble  com- 

T          T  '         T  " 

pound  lever  is  _  v  —  X  — 

Cl       Cl'       Cl" 


Figure  13 


Figure  14 


This  variety  of  levers  is  exemplified  in  (a)  the  Windlass  of  a 
(>nt,  in  which  the  Cl  is  the  radius  of  the  windlass  and  L  the  dis- 
tance from  the  axis  of  the  windlass  to  the  point  on  the  handspike 
where  the  men  take  hold,  when  raising  a  weight. 

(b)  Capstan — where  Cl  is  the  radius  of  the  drum  and  L  is 
the  length  of  the  capstan  bars. 

(c)  Crab — this  is  a  Compound  Lever  in  which  Cl  and  Cl'  are 
the  radius  of  the  smaller  gear  wheel,  and  L  and  L'  the  length  of 
the  windlass  arm  and  the  radius  of  the  larger  gear  wheel. 

The  mechanical  advantage  gained  by  a  lever  of  any  class  may 
be  figured  from  the  following: 


MECHANICAL    MANEUVERS 

For  Simple  Lever    _ 
Cl 

L       L' 
For  Compound  Lever  —  X  —  - 

V-<1  V^l 

wxci          wxci 

Power  to  be  applied  =  --  or  P  =  -- 

L  J-j 

T  vP  T   vP 

Weight  that  can  be  lifted     A,  or  W  =  ^—  - 


17 


THE    DIFFERENTIAL    PULLEY 

(See  Figure  15.) 


4J4? 


Figure  15 

This  machine  embodies  the  principles  of  the  revolving  lever, 
combined  with  a  single  movable  block. 

Two  pulleys  of  unequal  diameters,  having  a  common  axle,  are 
rigidly  attached  to  each  other;  an  endless  chain  passes  round  the 
larger  pulley,  A,  down  round  the  movable  pulley,  B,  and  up  round 
the  smaller  pulley;  the  upper  pulleys  are  sprocket  wheels,  that  is 
they  have  projecting  points  or  teeth  in  the  rims  into  which  the 


18  MECHANICAL    MANEUVERS 

links  of  the  chain  fit  to  prevent  its  slipping  when  a  weight  is  sup- 
ported. The  weight  is  suspended  from  the  lower  pulley,  B,  and  the 
force  is  applied  to  the  chain  at  P. 

The  power  of  this  tackle,  neglecting  friction,  is : 


/R-_r\ 

\   R    /' 


in  which  R  =  radius  of  large  pulley,  r  =  radius  of  small  upper 
pulley  and  the  factor  2  enters,  as  each  part,  c  and  d,  of  the  chain 
evidently  supports  one-half  the  weight  W. 

EXAMPLE : — If  the  radius  of  the  large  pulley  is  3  inches  and 
of  the  small  pulley  2^  inches,  the  power  of  the  tackle  will  be : 

Q    3OT/W- 12,  and  if  W  =  600  Ibs.,  P  =  ^  =  50  Ibs. 

O  £l/2/ 

HYDRAULIC  JACKS 

Nomenclature.  (See  Figure  16.)  There  are  two  kinds  of  Dud- 
geon 's  Hydraulic  Jacks ;  namely,  the  Base  Jack  and  the  Horizontal 
Jack.  Both  of  these  jacks  are  constructed  according  to  the  same 
principle  and  the  method  of  operation  is  the  same  for  both.  In 
Coast  Artillery,  the  horizontal  jack  only  is  used. 

A  Jack  is  a  lifting  machine.  It  is  operated  by  means  of  a  liquid 
acting  against  a  piston  to  raise  it ;  pressure  on  the  liquid  being 
produced  by  means  of  a  pump. 

A  force  of  a  few  pounds,  from  about  50  to  not  to  exceed  150, 
applied  at  the  end  of  the  pump  handle  or  lever,  produces  a  lifting 
force  of  from  15  to  60  tons  against  the  piston  of  the  ram. 

15,  20,  30,  and  60  Ton  Jacks  are  the  sizes  supplied  by  the  Ord- 
nance Department  and  these  jacks  may  be  used  equally  well  in  a 
horizontal  or  upright  position. 

According  to  the  principle  of  physics,  (Law  of  Pascal),  "When 
a  force  or  pressure  is  applied  to  a  fluid  contained  in  a  vessel,  this 
force  is  transmitted  equally  in  all  directions  throughout  the  fluid. ' ' 
Consequently  if  a  force  of  100  pounds  be  applied  through  a  pipe 
the  area  of  whose  cross  section  is  one  square  inch,  to  a  fluid  in  a 
vessel,  whose  area  is  100  square  inches,  the  resultant  force  will 
equal  100  times  the  original  force,  or  100  X  100  =  10,000  pounds. 
This  principle  is  made  use  of  in  the  jack,  for  in  its  application  to 
the  jack,  the  force  is  applied  through  a  small  pump  channel  to  the 
fluid  contained  in  the  ram  cylinder.  Assume  the  cylinder  to  be 
about  30  times  as  great  as  the  area  of  the  channel,  and  that  there 
is  100  pounds  of  pressure  transmitted  through  the  opening  of  the 
channel  to  the  cylinder,  then  the  piston  (which  just  fits  the  cylin- 


MECHANICAL   MANEUVERS 


19 


20  MECHANICAL    MANEUVERS 

der)  will  receive  an  upward  pressure  or  push  of  30  X  100  =  3000 
pounds.  In  other  words,  the  original  force  of  100  pounds  applied 
through  the  channel  to  the  fluid  contained  in  the  cylinder  is 
transmitted  equally  in  all  directions  in  the  cylinder,  and  on  each 
area  of  the  piston  equal  in  size  to  the  area  of  the  channel  is  exerted 
a  force,  (or  push)  equal  to  the  original  force  (100  Ibs.)-  As  there 
are  thirty  (30)  such  equal  areas  to  the  piston,  and  the  fluid  in  the 
cylinder  is  exerting  the  same  pressure  on  each  of  these  areas,  it 
is  easy  to  see  that  the  total  pressure  on  the  piston  is  thirty  times 
as  great  as  the  pressure  through  the  channel  where  the  area  of 
the  opening  of  the  channel  is  only  one-thirtieth  of  the  area  of  the 
piston. 

The  Hydraulic  Jack  makes  use  of  still  another  mechanical 
principle.  It  is  the  lever.  Examining  the  jack  it  is  seen  that  the 
pivot  comes  opposite  the  end  of  the  lever.  This  is  called  the 
Fulcrum  of  the  lever.  The  weight  (piston)  is  applied  about  one 
inch  from  the  piston  end,  or  fulcrum.  From  the  fulcrum  to  the 
end  of  the  handle  of  the  lever  where  the  force  is  applied  is  about 
25  inches.  This  makes  it  a  lever  of  the  second  class  (the  weight 
between  the  fulcrum  and  the  applied  force),  and  gives  a  decided 
mechanical  advantage ;  as  the  lever  arm,  or  power  arm  (the  distance 
from  the  pivot  or  fulcrum  to  the  point  where  the  power  is  applied) 
is  twenty-five  times  as  great  as  the  counter  lever  arm,  or  weight 
arm,  which  is  the  distance  between  the  fulcrum  and  the  point 
of  the  lever  when  the  weight  is  applied. 

The  Operation  of  the  Jack. 

1.  The  by-pass  channel  is  closed  by  screwing  down  the  lower- 
ing valve,  so  that  the  only  way  the  liquid  can  go  is  to  the  ram  in 
the  cylinder. 

2.  The  handle  of  the  piston  is  placed  in  its  socket,  with  the 
projection  downward. 

3.  Move  the  handle  of  the  piston  up  and  down,  which  pro- 
duces the  following  results : 

Motion  from  the  lever  is  transmitted  to  the  lever  socket, -thence 
to  the  knuckle  which  works  up  and  down  in  a  recess  of  the  piston 
and  forces  the  piston  up  and  down  in  the  reservoir.  The  down 
stroke  of  the  piston  closes  the  piston  valve,  and  the  pressure  com- 
presses the  pump  valve  spring,  opening  the  pump  valve,  thereby 
forcing  liquid  through  the  channel  to  the  ram  cylinder.  The 
ram  is  forced  up  by  pressure  of  the  liquid  in  the  cylinder  against 
the  lower  end  of  the  ram  as  explained  above.  On  the  up  stroke 
of  the  pump  piston,  the  pump  valve  spring  forces  the  pump  valve 
up  to  the  closed  position  and  prevents  the  return  of  any  fluid  from 


MECHANICAL    MANEUVERS  21 

the  cylinder  to  the  reservoir.  This  prevents  the  ram,  supporting 
the  weight,  from  dropping  down  as  the  liquid  is  confined  and  prac- 
tically non-compressible.  On  the  up  stroke  of  the  piston  the  piston 
valve  drops  down  in  the  piston  valve  bonnet  opening  a  passage 
for  the  fluid  which  flows  from  the  upper  portion  of  the  reservoir 
through  the  two  small  holes  in  the  piston  and  bonnet  to  replace 
the  fluid  under  the  piston  which  the  previous  down  stroke  of  the 
piston  has  forced  into  the  cylinder. 
Instructions  for  Using. 

1.  Be  sure  the  ram  is  down  before  filling. 

2.  Fill  with  one  part  alcohol  (not  wood  alcohol)  to  one  part 
water  with  a  teaspoonfull  of  sperm  oil  to  prevent  the  water  from 
rusting  the  cylinder. 

3.  Care  must  be  taken  that  no  dirt  gets  into  the  reservoirs 
in  filling. 

4.  Fill  reservoir  to  within  an  inch  of  the  top  and  replace 
the  screw  but  do  not  screw  up  tight  as  an  air  passage  is  cut  in  it. 

5.  Never  use  water,  kerosene,  heavy  oil,  or  glycerine  to  fill 
the  Jack.    Water  is  liable  to  freeze  and  would  rust  the  jack  when 
not  in  use.    Kerosene  destroys  the  packings  and  corrodes  the  metal 
surfaces.     Heavy  oiis  and  glycerine  soften  the  packing  and  gum 
.and  clog  the  valve  parts. 

6.  Occasionally  clean  out  the  jack  and  refill  it  as  the  liquid 
becomes  thick  and  the  jack  will  not  work  satisfactorily. 

7.  Always  keep  the  ram  down  when  not  in  use. 

8.  To  raise  the  weight,  screw  the  lowering  valve  tight  on  its 
-seat  and  work  the  lever  up  and  down. 

9.  To  lower  the  weight,   unscrew  the  lowering  valve — two 
turns  are  sufficient  to  lower  as  fast  as  required. 

10.  Use  the  claw  or  "S"  hook  when  the  jack  cannot  be  placed 
under  the  weight. 

FIELD  MANEUVERS 

The  implements  and  machines  required  for  the  various  opera- 
tions depend  upon  the  kind  and  weight  of  the  piece  and  the  nature 
of  the  maneuvers  to  be  performed.  For  each  exercise,  those 
specially  required  should  be  listed  carefully  and  should  be  on  the 
ground  before  the  work  commences.  When  work  is  to  be  done, 
due  allowance  must  be  made  for  the  wear  and  tear,  which,  with 
heavy  materiel,  is  very  considerable.  Sound  discretion  should 
be  exercised  not  to  allow  the  wearing  to  go  beyond  the  limit  of 
safety. 


22  MECHANICAL    MANEUVERS 

The  machines  and  appliances  usually  employed  for  moving: 
heavy  artillery  and  other  heavy  objects  are : 

Ropes,  Blocks  and  Tackles  Derricks 

Gins  Shears 

Hydraulic  Jacks  Blocks  and  Skids 

Sling  Carts  Chocks 

Hand  Spikes  Hand  Carts 

Railway  Trucks  Way  Planks 

Cradles  Pinch  Bars 

Capstans  Collars 

Tractors  Rollers 

These  are  sufficient  to  manage  the  heaviest  piece  of  Artillery 
in  the  cases  which  ordinarily  present  themselves  in  service. 

The  Capstan  is  used  as  a  strong  purchase  in  heaving  or  hoist- 
ing. When  so  employed,  it  is  held  in  position  by  a  stout  chain 
attached  to  hold-fasts.  The  rope  is  passed  two  or  three  times 
around  the  barrel  of  the  capstan,  the  free  end  coming  off  above 
the  turns ;  the  standing  part  is  attached  to  the  weight  to  be  moved. 
The  rope  is  drawn  taut  by  hand,  the  bars  inserted  in  the  mor- 
tises, and  the  free  end  of  the  rope  held  and  taken  in  by  two  men 
seated  on  the  ground. 

Twelve  men — three  at  each  bar — are  all  that  can  be  advan- 
tageously employed.  When  additional  power  is  required,  the  bars- 
are  swifted,  that  is,  the  ends  of  the  bars  are  lashed  together  with 
ropes,  by  which  additional  men  take  hold. 

A  Cradle  is  used  to  carry  a  gun  when  it  is  being  moved  on 
rollers.  It  consists  of  two  sections  of  Skids  of  suitable  strength 
and  length,  connected  by  two  cross  pieces  which  are  joined  and 
bolted  to  the  skids.  The  ends  of  the  Skids  are  beveled  off  on  the 
bottom  to  permit  engaging  the  rollers  easily.  The  cross  pieces  are 
hollowed  out  on  top  to  receive  the  gun.  The  gun  may  be  lashed 
to  the  cradle  if  necessary.  When  making  a  turn,  the  front  rollers 
should  be  inclined  in  the  direction  of  the  turn  and  the  rear  rollers 
in  the  opposite  direction.  The  rollers  may  be  knocked  into  place 
with  mauls.  A  body  moving  upon  a  roller  gains  twice  the  distance 
passed  over  by  the  roller. 

Blocks  are  rectangular  prisms  of  wood  employed  extensively 
in  all  operations  connected  with  the  movements  of  Heavy  Artillery. 

Skids  are  rectangular  beams  of  wood  used  for  similar  purposes. 

All  Blocks  and  Skids  should  be  sound,  free  from  knots,  and 
perfectly  true  dimensions.  When  the  edges  become  splintered 


MECHANICAL    MANEUVERS  23 

and  rounded  by  wear,  they  should  be  discarded,  as  with  such 
timbers  it  is  impossible  to  erect  safe  and  stable  cribbing  and  sup- 
ports. They  should  not  be  painted.  The  thickness  of  each  should 
be  marked  on  both  ends.  In  erecting  a  crib  or  other  support,  a  level 
foundation  is  of  the  first  consideration,  the  Blocks  should  then  be 
laid  crossing  each  other  in  alternate  tiers,  and  the  weights  sup- 
ported should  be  made  to  bear  equally  upon  all  sides  of  the  base. 

The  Way  Plank  is  an  oak  plank  15  feet  long,  12  inches  wide 
and  3  inches  thick.  Each  end  is  beveled  for  a  distance  of  6  inches, 
the  bevel  on  one  end  being  on  the  side  opposite  the  bevel  of  the 
other  end.  These  Planks  are  used  chiefly  for  forming  temporary 
tramways  for  rollers,  or  for  the  wheels  of  carriage  bearing  heavy 
weight. 

The  Pinch  Bar  is  simply  a  stout  handspike,  or  iron,  with  a 
round-beveled  butt,  turned  up  into  a  blunt  edge  for  the  purpose 
of  catching  under  a  gun  or  other  similar  object.  It  is  used  as  a 
lever,  by  pressing  down,  thus  jumping  the  gun  forward  a  very 
short  distance  at  a  time.  The  butt  end  is  of  steel.  The  length  of 
the  bar  is  from  five  to  seven  feet. 

The  Collar  is  a  device  placed  upon  the  chase  of  a  gun  to  make 
its  diameter  equal  to  that  of  the  body  of  the  piece.  This  enables 
the  gun  to  be  rolled  with  facility.  It  is  made  of  pieces  of  scan- 
tling joined  together  after  the  manner  of  the  staves  of  a  cask, 
and  hooped  with  stout  bands  of  iron.  It  is  shoved  over  the  muz- 
zle onto  the  chase,  and  secured  with  wedges  of  wood. 

Chocks  are  made  of  solid  oak  wood,  of  various  shapes  and  di- 
mensions, those  of  triangular  cross  section  being  most  common. 
The  grain  of  the  wood  runs  lengthwise  with  the  chock. 

All  implements  and  machines  before  being  used,  should  be 
most  carefully  examined  in  every  detail,  to  see  that  they  are  ser- 
viceable and  suitable  for  the  operation  to  be  performed.  None 
should  be  put  to  uses  for  which  they  are  not  intended,  nor  sub- 
jected to  strains  they  are  not  constructed  to  bear. 

It  must  be  borne  in  mind  that  the  giving  away  of  one  part 
breaks  and  destroys  other  parts,  frequently  to  an  extent  not  readily 
repaired,  and,  furthermore,  endangers  those  working  at  the  ma- 
neuvers. Heavy  weights  must  never  be  allowed  to  drop,  even  for 
the  shortest  distances;  they  must  be  lowered  to  rest  with  a  gentle 
motion,  and  at  the  same  time  chocked  to  prevent  rolling  or  sliding. 
In  hoisting,  they  must,  when  practicable,  be  closely  followed  up 
with  blocks  or  chocks  to  guard  against  any  possible  giving  way. 
All  motions  with  heavy  bodies  must  be  slow,  so  as  not  to  generate 
momentum.  Supports  must  have  a  firm  base,  and  cribbing  a  level 


24  MECHANICAL    MANEUVERS 

foundation,  and  be  built  up  vertically.  All  holdfasts  must  be 
secure  beyond  possibility  of  giving  away. 

Two  or  more  men,  lifting  or  hauling  together,  must  wait  for 
the  command  before  exerting  their  strength.  The  officer  in  charge 
sees  that  all  are  ready  before  giving  the  command  HEAVE. 
Then  all  move  with  a  prompt  but  steady  effort,  and  apply  their 
power  increasingly  until  the  weight  responds  to  their  effort.  The 
command  will  be  repeated  as  often  as  it  may  be  necessary.  When 
the  movement  has  been  sufficiently  made,  the  command  EASE 
AWAY  is  given.  Those  making  the  effort  will  then  desist;  but 
at  all  times  will  be  careful  to  avoid  all  sudden  shocks  or  strains. 
Every  operation  should  be  done  with  spirit  and  animation,  but 
without  bustle  or  confusion.  Vigilance  should  be  constantly  ex- 
ercised to  have  the  piece  or  rollers  securely  chocked. 

When  lifting  a  gun  with  Jacks,  be  sure  and  lift  one  end  of  the 
gun  at  a  time,  the  other  being  chocked  on  the  cribbing. 

A  greased  steel  rail  on  top  of  a  Skid  will  greatly  facilitate 
sliding  a  gun  or  slueing  the  trunnions. 

The  Handspikes  used  in  mechanical  maneuvers  are  beveled 
on  one  side,  as  these  will  enter  into  places  or  under  bodies  where 
square  handspikes  could  not  be  used.  When  a  handspike  rests 
on  a  fulcrum,  and  the  weight  on  one  end  is  to  be  raised  by  bearing 
down  on  the  other,  the  weight  should  never  rest  on  the  beveled 
side,  as  the  handspike  would  not  then  give  a  good  hold,  and  would 
be  liable  to  split.  In  this  case  the  beveled  side  should  be  down, 
but  if  used  for  lifting,  as  when  two  handspikes  are  crossed  under 
the  breech  or  chase  of  a  gun  to  heave  it  upward,  their  ends  resting 
on  the  ground  or  platform,  the  beveled  side  should  be  up. 

Parbuckling  is  the  best  method  of  rolling  a  gun.  To  do  this, 
place  the  gun  on  skids,  and  attach  the  rope  by  a  bowline  to  one 
of  the  trunnions,  passing  it  under  and  around  up  over  the  gun, 
and  hauling  on  the  end.  If  the  gun  is  to  be  rolled  up  a  slope,  two 
ropes  of  size  suitable  to  the  weight  of  the  gun,  are  used.  An  end 
of  each  rope  is  made  fast  to  some  fixed  object  at  the  upper  part 
of  the  slope;  the  other  ends  are  carried  under  the  chase  and  body 
respective^,  and  up  over  the  gun,  these  ends  are  hauled  upon  by 
means  of  a  capstan,  or  by  attaching  to  them  a  fall  and  tackle. 
The  muzzle  is  slued  forward  when  necessary,  to  compensate  for  the 
greater  distance  traveled  by  the  breech. 

To  Cross-Lift  a  piece  or  other  object  is  to  cross  handspikes 
under  it  from  opposite  sides.  The  butt  end  of  the  handspikes  is 
on  the  ground,  and  the  power  is  applied  by  lifting  at  the  other  end. 


MECHANICAL    MANEUVERS  25 

To  Slue  the  Trunnions  is  to  turn  the  piece  on  its  axis  so  as  to 
bring  the  trunnions  into  any  required  position.  This  is  done  by 
first  placing  the  piece  on  skids  perpendicularly  to  its  axis.  A 
fulcrum  is  placed  near  the  trunnion  to  be  raised;  upon  this  a 
handspike  or  other  lever  is  used,  the  piece  meanwhile  being  chocked 
on  the  opposite  side,  or  a  trunnion  loop  may  be  placed  around  the 
trunnion  to  be  raised,  and  a  handspike  or  lever  passed  through  it, 
with  the  butt  end  resting  on  the  top  of  the  piece,  the  power  applied 
by  lifting  at  the  other  end,  the  piece  being  chocked  as  before.  Or, 
by  passing  the  bight  of  a  rope  once  or  twice  around  the  piece  and 
placing  the  butt  of  a  handspike  or  lever  through  the  bight,  and 
bearing  down  or  lifting  up,  using  the  piece  as  a  fulcrum,  the  ends 
of  the  rope  being  held  to  prevent  them  from  slipping.  All  three 
of  these  methods  may  be  used  at  the  same  time.  The  skids  should  be 
well  greased  under  the  piece,  and  likewise  should  be  the  chocks. 
When  the  piece  is  of  great  weight,  the  hydraulic  jack  or  gin  is 
advantageously  used,  provided,  the  axis  of  the  trunnions  are  not 
vertical.  The  former  is  placed  under  and  the  latter  over  the 
trunnion  to  be  raised.  When  the  axis  of  the  trunnions  is  vertical 
or  nearly  so,  a  rope  is  passed  around  the  gun  and  made  fast  to 
one  of  the  trunnions  in  a  manner  similar  to  the  parbuckling  ar- 
rangement and  hauled  upon  with  tackle;  meanwhile  keeping  the 
gun  from  rolling  with  greased  chocks.  The  chock  may  be  kept  in 
place  by  passing  a  rope  around  its  end,  under  the  gun  along  each 
slide  of  the  skid  and  making  fast  around  the  end  of  the  skid. 

To  Pinch  a  gun  or  other  object  is  to  move  it  by  small  heaves 
with  a  pinch-bar  or  handspike,  without  allowing  it  to  turn  on  its 
axis.  A  piece  is  pinched  one  end  at  a  time,  the  other  being  chocked. 
The  bar  or  handspike  is  placed  as  a  lever,  with  the  beveled  side 
down,  and  the  power  applied  at  the  other  end  by  bearing  down. 

To  Launch  a  piece  or  other  object  forward  or  backward  is  to 
move  it  in  the  direction  of  its  axis.  If  the  weight  is  such  as  to 
require  levers  or  handspikes,  they  are  placed,  usually,  on  opposite 
sides,  and  the  power  applied  by  bearing  down,  at  the  same  time 
carrying  the  free  end  of  the  lever  in  a  direction  contrary  to  that 
in  which  the  object  is  to  be  moved. 

To  Slue  a  piece  or  other  object,  end  for  end,  is  to  turn  it  around, 
not  allowing  it  to  revolve  on  its  longer  axis. 

The  muzzle  may  be  slued  by  pinching  it  along  skids,  or  by 
placing  a  roller  or  skid  in  the  muzzle  and  hauling  upon  it  with 
tackle.  Probably  the  best  way  of  slueing  the  muzzle  of  a  heavy 
gun,  is  by  means  of  a  hydraulic  jack  and  greased  chock.  Jack  up 
the  muzzle  until  the  inclined  edge  of  the  chock  can  be  placed  well 


26  MECHANICAL    MANEUVERS 

under.  Lower  away  on  the  jack,  keeping  the  chock  firmly  in 
place  and  allowing  the  muzzle  to  slide  down  its  edge  and  onto 
the  skid.  The  jack  will  incline  to  one  side  and  should  be  steadied 
to  keep  it  from  falling. 

To  Cut  is  to  move  the  object  horizontally,  without  rolling,  by 
moving  each  end  alternately  in  the  required  direction. 

USE  OF  TRACTOR 
OCCUPATION  OF  POSITION  BY  TACKLE 

The  occupation  of  position  by  tackle  would  only  arise  when  it 
was  desired  to  keep  the  tractor  on  the  road  so  as  to  avoid  making 
tracks  which  would  destroy  the  concealment  of  the  position  or  when 
the  position  is  so  narrow  that  the  tractor  cannot  go  ahead  of  the 
gun  and  put  the  latter  in  its  position.  With  Wheeled  Tractors, 
this  method  is  used  not  only  to  avoid  making  tracks,  but  also  be- 
cause frequently  the  soil  is  too  soft  and  heavy  to  permit  of  the 
tractor  entering  the  position. 

With  any  type  of  Tractor,  this  method  necessitates  the  use  of 
a  holdfast  for  the  block  of  the  tackle  at  the  position.  Holdfasts 
may  be  available  in  the  form  of  the  walls  of  a  standing  or  ruined 
building,  trees,  etc.  A  tree  should  only  be  used  if  well  grown  and 
sound.  The  strap  should  be  placed  as  near  the  butt  as  possible 
and  still  keep  the  ropes  of  the  tackle  off  the  ground.  The  excel- 
lence of  the  following  trees  as  holdfasts  in  general  is  in  the  order 
named:  Oak,  Beech,  Chestnut,  Willow,  Birch. 

The  best  artificial  holdfast  is  the  Deadman.  Dig  a  cross 
trench  at  least  five  yards  beyond  the  battery  position,  one  yard 
and  a  half  long,  twenty  inches  wide  and  one  yard  deep.  At  right 
angles  to  its  middle  point  dig  an  inclined  trench  to  the  bottom  for 
the  strap  of  the  tackle.  Place  a  plank  one  yard  and  a  half  x  12"  x 
3"  on  edge  at  the  bottom  of  the  trench  on  the  near  side,  then  drive 
in  four  stout  stakes  behind  this  plank.  Now  drop  in  a  log  or 
timber  about  12"  in  diameter,  with  the  strap  around  it,  behind 
the  four  vertical  stakes;  drive  four  stakes  obliquely  into  the  rear 
side  of  the  trench,  bearing  on  the  log ;  then  drop  into  place  between 
the  near  wall  and  the  vertical  stakes  another  plank  one  yard  and 
a  half  x  12"  x  3". 

The  kind  of  tackle  to  use  generally  depends  more  on  the  strength 
of  the  rope  than  on  the  power  of  the  tractor.  In  general,  with 
good  rope,  the  luff  tackle  is  sufficiently  powerful.  With  extremely 
soft  ground  or  on  a  steep  slope,  depending  on  the  kind  of  gun,  the 
four-foul  tackle,  two  double  blocks,  or  the  five-fold  tackle,  a  triple 


MECHANICAL    MANEUVERS  27 

block  and  double  block,  may  be  required.  Always  err  on  the  side 
of  choosing  too  powerful  a  tackle. 

Safety  Tackle.  Whenever  the  gun  has  to  be  moved  up  or  down 
a  very  steep  slope,  a  safety  tackle  of  equal  strength  with  the 
maneuvering  tackle  should  be  reeved  and  attached  to  the  gun  and 
made  fast  to  a  separate  holdfast,  The  fall  may  be  led  to  any 
convenient  and  secure  means  of  snubbing  it.  One  or  more  men 
should  be  detailed  to  handle  this  tackle.  If  the  gun  is  being  raised, 
the  safety  tackle  should  be  rounded  in  constantly  to  keep  it  taut, 
the  fall  being  snubbed  the  while.  If  the  gun  is  being  lowered,  the 
safety  tackle  should  be  paid  out  to  keep  pace  with  the  movement 
of  the  gun.  Or  the  second  tackle  may  be  led  to  the  pintle  of  another 
tractor,  and  thus  become  a  power  tackle. 

Use  of  Power  Other  Than  the  Tractor.  The  maneuver  of  guns 
or  other  heavy  vehicles  may  be  accomplished  by  the  use  of  tackle 
according  to  the  above  principles  with  either  horse-draft  or  man- 
power on  the  fall.  For  the  execution  of  difficult  slow  movements 
horse-power  is  not  satisfactory.  With  the  size  of  rope  ordinarily 
furnished,  not  over  forty  men  should  be  put  on  the  fall  of  a  tackle 
in  situations  where  the  breaking  of  the  rope  would  endanger  the 
gun.  With  the  use  of  large  cable,  200  men  have  been  used  effec- 
tively on  the  fall  of  a  tackle. 

Crossing  of  Ditches.  Ditches  should  be  bridged  by  heavy 
planks  or  filled  with  fascines. 

Very  Soft  or  Muddy  Ground.  Should  be  crossed  by  the  use 
of  mats  or  by  laying  heavy  planks  crosswise  for  the  wheels  to  run  on. 

USE  OF  TACKLE  WITH  THE  HOLT  TRACTOR 

The  Holt  Tractor  not  being  provided  with  a  capstan,  the  fall 
of  the  tackle  is  handled  by  making  it  fast  to  the  tractor,  which 
then  moves  off  the  desired  distance,  the  fall  being  cast  off  and 
the  tractor  backing  up  when  necessary  for  a  new  hold.  A  man 
should  be  detailed  to  the  fall,  making  fast  to  the  tractor  pintle 
by  a  blackwall  hitch  and  retaining  the  free  end  in  his  hand. 
Another  man  should  be  detailed  at  the  holdfast,  to- keep  the  block 
straight  and  the  rope  clear. 

If  it  is  desired  to  keep  the  tractor  on  the  road  it  will  generally 
be  necessary  to  change  the  direction  of  the  fall  by  the  use  of  a 
snatch  block  on  a  second  holdfast.  For  this  holdfast  it  may  be 
convenient  to  use  another  Holt  tractor,  particularly  if  the  change 
of  direction  is  not  too  abrupt. 

Simultaneous  Maneuvering  of  Guns.  The  time  that  the  guns 
are  occupying  or  leaving  a  position  is  generally  a  most  critical 


28  MECHANICAL    MANEUVERS 

period  for  the  safety  of  the  Battery.  Therefore  every  means 
should  be  taken  to  shorten  this  period.  Whenever  the  approach 
to  the  position  will  permit  the  simultaneous  maneuvering  of  the 
guns,  the  work  should  be  planned  so  that  all  guns  may  be  put  into 
position  by  their  own  tractors  simultaneously,  even  if  it  is  nec- 
essary to  install  a  deadman  for  each  gun.  Sometimes  it  will  happen 
that  one  or  more  guns  may  be  put  in  position  by  direct  traction 
while  the  others  are  being  put  in  by  tackle. 

Use  of  One  Holdfast  for  More  Than  One  Gun.  It  will  fre- 
quently occur  that  a  suitable  natural  holdfast  is  not  on  a  line 
through  any  one  gun  position  at  right  angles  to  the  battery  front. 
However,  by  starting  each  gun  from  a  position  on  the  road  such 
that  a  line  from  the  gun  to  the  holdfast  will  cross  the  gun  position, 
such  a  holdfast  may  be  made  to  serve  for  two  guns. 

Use  of  Two  Holdfasts  for  One  Gun.  On  other  occasions  no 
one  natural  holdfast  will  lead  a  gun  to  its  position,  but  by  leading 
one  or  more  parts  of  the  tackle  to  another  block  at  a  holdfast 
situated  at  a  distance  on  the  other  side  of  the  direct  line  to  the 
position  from  which  the  first  holdfast  is  located,  it  will  be  possible 
to  haul  the  gun  and  direct  it  to  its  position.  The  influence  on  the 
steering  of  the  gun  of  the  number  of  parts  of  the  tackle  led  to  each 
holdfast  must  be  considered. 

Handling  Artillery  in  Mountainous  Country.  This  is  a  subject 
which  deserves  special  consideration.  There  are  conditions  of 
Alpine  warfare  which  require  the  emplacing  of  guns  in  almost 
inaccessible  places.  To  emplace  the  guns  and  also  to  maintain  their 
ammunition  supply,  resort  has  been  had  to  aerial  cableways  and 
other  complicated  and  extensive  use  of  cordage  and  tackle  which  is 
outside  the  scope  of  the  contemplated  work  of  Tractor  Artillery. 
However,  in  order  to  fulfill  its  mission  Tractor  Artillery  may  need 
to  emplace  its  guns  in  very  difficult  positions.  In  order  to  meet 
these  conceivable  situations,  it  is  first  of  all  necessary  to  accept  as  a 
fundamental  principle  that  given  the  necessary  time  and  equip- 
ment, any  tractor  weapon  can  be  emplaced  anywhere.  The  Prac- 
tical applications  of  this  principle  by  the  limitations  imposed  by 
the  tactical  situation  upon  the  Time  and  Equipment  to  be  used 
in  consideration  of  the  object  to  be  attained,  ordinarily  results  in 
the  selection  of  very  easily  accessible  positions  for  Tractor  Artillery. 

Negotiating  a  Bad  Turn  on  a  Mauntain  Road.  If  the  turn  is  so 
sharp  as  to  preclude  the  tractor  or  tractors  making  the  curve  with 
the  gun  attached,  it  may  be  possible  to  uncouple  the  tractor,  run 
it  round  the  turn,  and  then  draw  the  gun  around  the  turn  with 
tackles.  For  the  first  pull,  it  may  be  necessary  to  carry  the  rope 


MECHANICAL    MANEUVERS  29 

from  the  gun  through  a  snatch  block  at  a  holdfast  on  the  upper 
:side  of  the  road.  Then  after  the  gun  has  completed  part  of  the  turn 
the  rope  may  be  released  from  the  snatch  block  for  a  direct  pull. 
If  the  turn  is  so  abrupt  that  the  gun  alone  cannot  negotiate  it, 
there  are  still  two  recourses.  1st:  the  road  may  be  widened.  If 
the  soil  is  such  as  to  make  this  difficult,  haul  the  gun  directly  up 
the  slope  from  the  lower  reach  of  the  road  below  the  turn  to  the 
upper  reach  above  the  turn.  To  do  this,  select  three  stout  trees 
above  the  upper  road  for  holdfasts,  or  install  deadmen.  Rig 
two  heavy  maneuvering  tackles  and  one  safety  tackle.  Run  the 
tractor  or  tractors  hauling  the  gun  around  the  curve  and  up  out 
of  the  way.  Attach  one  maneuvering  tackle  to  the  limber,  not  to 
the  draw-bar,  and  ca-rry  its  fall  through  a  snatch  block  at  a  hold- 
fast on  the  lower  road,  back  of  the  gun,  to  the  tractor  following. 
Attach  the  second  maneuvering  tackle  to  the  Gun  Carriage  proper, 
leading  its  fall  similarly  through  another  snatchblock  to  a  second 
tractor  on  the  lower  road.  Attach  the  safety  tackle  to  the  limber. 
Using  both  maneuvering  tackles,  haul  the  gun  up  the  slope,  turning 
and  steering  it  by  slings  tied  to  the  drawbar,  leading  to  either  side, 
with  the  necessary  number  of  men,  6  or  8,  on  each  sling.  After  the 
limber  wheels  surmount  the  edge  of  the  upper  road  take  most  of 
the  strain  on  the  tackle  to  the  carriage  itself,  so  as  to  facilitate 
steering  the  gun  into  its  position  on  the  road.  The  fall  of  a  tackle 
should  never  be  led  directly  to  a  tractor  on  the  upper  road,  as  the 
sudden  failure  of  a  holdfast  might  drag  the  tractor  off  the  road 
before  the  tackle  would  yield  to  over  hauling. 

Emplacing  a  Gun  in  a  Position  With  Steep  Approaches.  In  gen- 
eral it  may  be  said  that  even  if  there  is  a  road  of  suitable 
gradient  to  the  position,  if  this  road  is  not  amply  wide  with  prac- 
ticable curves,  it  is  safer  to  handle  the  gun  by  tackle,  by  the 
means  indicated  in  the  preceding  paragraph.  The  important  point 
to  observe  is  that  the  gun  must  be  handled  Straight  Up  the  slope. 
Only  by  this  means  can  it  be  kept  bearing  on  its  wheels  and  avoid 
overturning  sidewise. 

Lowering  a  Gun  Down  a  Steep  Slope.  The  three  tackles 
should  be  made  fast  to  the  gun  carriage  and  the  gun  lowered, 
limber  first.  The  man  steering  the  limber  should  use  slings  long 
•enough  so  that  they  would  not  be  caught  by  either  the  gun  or 
tackle  in  case  of  accident.  Here  again  the  important  thing  is  to 
avoid  any  tendency  for  the  gun  to  overturn  sidewise  by  keeping 
it  headed  straight  down  the  slope,  thus  providing  equal  bearing 
for  all  the  wheels.  As  an  additional  precaution,  the  falls  after 
"being  led  away  from  the  tractor,  should  be  snubbed  around  a 


30  MECHANICAL    MANEUVERS 

tree,  and  an  additional  man  detailed  to  keep  the  fall  paying  out 
freely  at  the  tree,  but  ready  to  snub  it  instantly  when  directed. 

Rescuing  Mired  and  Overturned  Vehicles.  If  a  motor  vehicle 
becomes  mired,  chains  should  be  put  on  if  not  already  on,  and  in 
using  its  own  power,  the  motor  should  not  be  accelerated  exces- 
sively. Opening  the  throttle  wide  generally  serves  merely  to 
spin  the  wheels,  digging  a  deeper  hole  for  the  machine  to  drop 
into.  By  using  the  clutch  carefully,  it  is  often  possible  to  get 
traction  by  short  grips,  without  stalling  the  motor  or  digging  deep 
holes. 

A  vehicle  which  runs  or  slides  partly  off  the  road  should  always 
back  out  rather  than  try  to  go  ahead  and  steer  up  onto  the  road. 
If  there  is  another  machine  behind,  it  should  give  a  tow,  even  if 
only  a  light  car.  The  towline  should  be  made  fast  to  the  frame 
rather  than  the  front  axle,  and  if  possible,  should  be  ten  yards 
long. 

A  vehicle  which  has  overturned  should  first  of  all  be  unloaded 
Then  if  the  ground  is  soft  and  the  vehicle  is  heavy,  planks  should 
be  placed  under  the  lower  wheels  and  the  brakes  set.  If  jacks; 
are  available,  one  should  be  used  under  either  end  as  far  up  on  the 
body  as  the  strength  of  the  body  will  permit.  Follow  up  the  work 
of  the  jack  with  blocking,  improvised  if  necessary,  and  when 
the  jack  has  reached  its  limit,  give  it  a  new  footing  with  blocking.. 
Before  the  vehicle  raises  high  enough  to  right  itself,  secure  it  by  a 
guy  rope  so  that  it  will  not  right  itself  with  a  crash,  either  snub- 
bing the  guy  rope  or  using  men  on  the  fall.  Or  a  shear  may  be 
rigged.  A  light  car  or  truck  may  be  righted  by  the  effort  of  the 
number  of  men  who  can  assemble  around  it.  In  any  event,  what- 
ever means  is  used  to  lift  the  vehicle,  all  men  available  should  bear 
a  hand,  using  improvised  levers  if  possible. 

THE   GIN 

A  Gin  is  a  tripod  formed  of  three  poles.  Two  of  these  poles: 
called  legs,  are  joined  together  by  braces  of  wood  or  iron  and 
contained  between  them  the  Windlass.  The  third  pole  is  called  the 
Prypole,  and  is  joined  to  the  Legs,  at  the  top,  by  a  bolt.  This  bolt 
supports  a  Clevis  to  which  the  upper  block  of  the  tackle  is  hooked. 

The  Windlass  is  worked  by  two  handspikes  fitting  into  brass 
sockets,  one  at  each  extremity  of  the  windlass ;  the  operation  of  the 
handspikes  is  made  continuous  by  the  action  of  a  Pawl  attached 
to  the  socket  on  the  Ratchet  of  the  windlass. 

The  Prypole  has  cleats  nailed  to  it  to  enable  a  man  to  mount  to. 
the  head  of  the  gin  to  hook  on  the  block  and  to  reeve  the  fall. 


MECHANICAL    MANEUVERS 


31 


To  prevent  the  legs  and  prypole  from  sinking  into  the  ground, 
or  injuring  the  pavement  of  casemates,  stout  pieces  of  wood, 
called  Shoes,  are  placed  under  them. 

GARRISON  GIN 

The  Hoisting  apparatus  consists  of  two  blocks,  through  which 
the  fall  is  rove.  The  fall  is  wound  two  or  more  times  around  the 
windlass. 

There  are  three  kinds  of  Gins  used  for  Artillery  purposes,  the 
Siege,  the  Garrison,  and  the  Casemate. 

The  last  two  differ  from  each  other  only  in  height;  the  first 
differs  from  the  others  in  construction  and  size.  Piper's  Gin  is  an 
improved  modification  of  the  Siege  Gin. 


GARRISON  GIN 

Figure  17.     Garrison    Gin 

The  Siege  Gin  (Old  pattern)  has  no  Clevis,  as  other  gins, 
instead  of  an  upper  block,  two  Sheaves  are  inserted  between  the 
legs  and  secured  by  the  bolt  holding  together  the  legs.  The  head 
of  the  prypole  is  terminated  by  a  flat  piece  of  iron,  which  fits 
between  the  heads  of  the  legs  above  the  sheaves  and  is  secured  by 
another  bolt. 

This  gin  further  differs  from  others  in  having  three  wooden 
braces  instead  of  two  of  iron.  It  has  the  disadvantage  of  being 
exceedingly  ill-contrived  and  unhandy. 

The  Garrison  and  Casemate  Gins  differ  from  the  siege  gin  in 
having  two  cross-bars,  and  in  having  the  prypole  inserted  between 


"32  MECHANICAL    MANEUVERS 

the  legs,  which  are  kept  together  by  the  Clevis  Bolt.  The  upper 
block  (generally  treble)  is  hooked  to  the  clevis. 

The  casemate  gin  is  made  shorter  than  the  garrison  gin,  so 
that  it  may  be  hoisted  in  casemates. 

When  the  gin  is  put  together  and  raised,  that  part  included 
between  the  legs  and  the  prypole  is  called  the  inside,  the  outside 
being  the  part  without  the  legs;  the  right  corresponding  to  the 
right  hand  of  a  man  standing  at  the  middle  and  outside  of  the 
windlass,  facing  towards  it. 

The  detachment  is  composed  of  1  sergeant,  1  corporal,  and  10 
privates.  The  odd  numbers  are  placed  on  the  right  and  the  even 
numbers  on  the  left  side  of  the  gin,  all  facing  inwards.  Nos.  1  and 
2  opposite  and  one  yard  outside  of  the  foot  of  the  Prypole ;  No.  9 
outside  of  and  near  the  foot  of  the  right  leg;  No.  10,  outside  of 
and  near  the  foot  of  the  left  leg ;  Nos.  3,  5,  and  7  are  between  Nos. 
1  and  9,  dressing  on  them  and  dividing  the  intervening  space  into 
equal  distances;  Nos.  4,  6,  and  8,  occupy  similar  positions  with 
respect  to  Nos.  2  and  10.  In  assembling  the  Gin  the  Corporal 
-and  Nos.  1  and  2  bring  up  the  prypole ;  Nos.  3,  5,  and  7,  the  right 
leg,  and  Nos.  4,  6,  and  8  the  left  leg;  Nos.  9  and  10  the  windlass. 
The  Corporal  superintends  putting  together  the  head,  and  the 
Sergeant  the  placing  of  the  windlass.  The  braces  are  brought  up 
•and  adjusted  to  their  places  by  Nos.  4,  6,  7,  and  8. 

All  except  the  old  pattern  Siege  Gin  are  put  together  and 
hoisted  by  raising  the  head  and  bringing  up  the  foot  of  the  prypole 
towards  the  foot  of  the  legs. 

The  gin  may  be  put  together  across  the  piece,  or  on  the  ground 
near  it,  lying  extended  in  the  form  of  a  T  with  the  inside  down. 

The  gin  being  together  and  lying  on  the  ground,  the  Sergeant 
commands  RAISE  THE  GIN. 

In  raising  it  Nos.  9  and  10,  each  with  a  handspike,  brace  against 
the  lower  cross-bar  near  the  legs  to  prevent  them  from  slipping; 
Nos.  1  and  2  hold  down  the  foot  of  the  prypole,  and  at  the  same 
time  push  up  by  the  handle.  The  remaining  numbers  take  hold  to 
lift  by  hand  near  the  head. 

The  Corporal  commands  HEAVE,  the  head  of  the  gin  is  raised 
as  high  as  the  men  can  lift,  and  the  prypole  is  pushed  up;  Nos.  3 
and  4  go  to  the  assistance  of  Nos.  1  and  2  at  the  handle  of  the 
prj'pole;  Nos.  5,  6,  7,  and  8,  lift  the  legs  on  their  respective  sides. 
The  command  HEAVE  is  repeated  until,  by  successive  efforts, 
the  gin  is  raised.  The  prypole  should  be  for  the  garrison  gin, 
about  seventeen  feet  from  the  legs;  for  the  casemate  gin,  about 
thirteen  feet. 


MECHANICAL    MANEUVERS  33 

The  gin  is  next  placed  over  the  piece  by  moving  the  legs  and 
prypole  each  a  short  distance  at  a  time.  To  prevent  them  from 
spreading  too  much,  a  lashing  is  passed  from  the  prypole  to  the 
legs  or  to  the  cross-bar. 

To  Reeve  the  Fall,  fasten  one  end  of  a  trace  rope  to  the  upper 
block  by  passing  it  through  the  shell  of  the  block.  An  expert  man 
ascends  the  prypole  to  the  head,  and  passes  the  free  end  of  the 
rope  through  the  clevis,  from  whence  it  is  carried  to  the  ground. 
By  heaving  on  the  rope,  the  block  is  raised  and  the  hook  passed 
through  the  clevis,  with  its  point  towards  the  prypole.  The  fall 
is  rove  as  explained  for  any  tackle.  The  upper  block  may  be 
hooked  to  the  clevis  and  raised  with  the  gin;  the  fall  may  also 
be  rooved  and  the  whole  raised  together.  The  extra  weight  thus 
given  makes  the  gin  more  difficult  to  lift. 

The  Corporal  assisted  by  the  most  expert  Privates,  slings  the 
piece,  and  attends  to  all  knotting  and  lashings. 

In  working  the  windlass,  Nos.  1  and  2  hold  on  to  the  fall  and 
take  up  the  slack;  Nos.  7  and  9  work  at  the  right,  and  Nos.  8  and 
10  at  the  left  handspike,  Nos.  7  and  8  being  next  to  the  windlass. 

To  move  the  gin  Nos.  1  and  2  station  themselves  at  the  handle 
of  the  prypole;  Nos.  9  and  10  each  place  a  handspike  under  the 
windlass  from  without,  and  near  the  legs;  Nos.  7  and  8  assist  to 
lift  these  handspikes  from  within;  at  the  command  all  move  in 
the  direction  indicated. 

The  gin  is  lowered  in  a  similiar  manner,  but  by  inverse  means 
to  that  prescribed  for  raising  it,  by  gradually  drawing  out  the 
prypole  until  the  men  can  get  near  enough  towards  the  head  to 
support  it;  it  is  then  lowered  upon  the  piece  or  on  the  ground;  as 
the  case  may  be. 

A  gun  may  be  moved  horizontally  with  the  gin  by  moving  the 
head  of  the  gin  two  or  three  feet  in  the  direction  in  which  the 
gun  is  to  be  moved.  By  hauling  away  on  the  windlass  the  gun 
may  be  made  to  slide  along  the  skids  until  it  is  directly  under  the 
head  of  the  gin.  This  operation  may  be  repeated  until  the  gun 
is  in  the  desired  position. 

The  lifting  capacity  of  the  garrison  gin  is  17,000  pounds. 

A  Gin  may  be  improvised  by  lashing  three  timbers  together 
arid  erecting  them  in  the  form  of  a  tripod.  The  lashing  is  made 
as  follows:  Mark  on  each  spar  the  distance  from  the  butts  to  the 
center  of  the  lashing.  Lay  two  of  the  spars  parallel  to  each  other 
with  an  interval  a  little  greater  than  the  diameter.  Rest  their 
tips  on  a  skid  and  lay  the  third  spar  between  them  with  its  butt 
in  the  opposite  direction  so  that  the  marks  on  the  three  spars 


34  MECHANICAL    MANEUVERS 

will  be  in  line.  Make  a  clove  hitch  on  one  of  the  outer  spars 
below  the  lashing  and  take  eight  or  nine  loose  turns  around  the 
three.  Take  a  couple  of  frapping  turns  between  each  pair  of 
Spars  in  succession  and  finish  with  a  clove  hitch  on  the  central 
spar  above  the  lashing.  Pass  a  sling  over  the  lashing  and  the 
tripod  is  ready  for  raising. 

SLING  CART 

The  Sling  Cart  is  used  for  moving  guns  or  other  heavy  objects 
short  distances. 

There  are  two  kinds :  The  Garrison  Sling  Cart,  for  the  heaviest 
weights,  is  attached  by  its  pole  to  a  limber,  or  on  the  Hand  Sling 
Cart,  and  may  be  drawn  by  horses;  the  Hand  Sling  Cart  is  de- 
signed for  moving  lighter  wreights  by  hand. 

With  the  hand  sling  cart  the  weight  is  raised  sufficiently 
from  the  ground  to  transport  it  by  first  attaching  a  sling  of  the 
proper  length  to  the  weight  to  be  moved  and  then  raising  the  pole 
uf  the  cart  enough  to  permit  the  hook  on  the  rear  of  the  axle  being 
Jiocked  into  this  sling.  The  pole  in  this  case  is  used  as  a  lever, 
the  axle  and  wheels  form  the  fulcrum,  and  the  weight  is  raised 
by  lowering  the  end  of  the  pole.  It  may  be  used  for  transporting 
any  weight  up  to  6000  pounds. 

,  With  the  garrison  sling  cart  the  weight  is  raised  by  first 
attaching  to  it  a  sling,  and  then  applying  to  the  sling  the  hooks 
forming  the  lower  part  of  a  powerful  screw  passing  up  through 
the  axle  of  the  cart.  Above  the  axle  is  the  nut  of  the  screw,  pro- 
vided with  long  handles  by  means  of  which  the  screw  is  run  up, 
thus  raising  the  weight. 

The  sling  cart  is  capable  of  supporting  20,000  pounds. 

SHEARS 

Shears  consist  of  two  parts  of  suitable  size  for  the  weight  to 
be  raised,  lashed  together  in  the  form  of  an  inverted  F,  suitably 
guyed  and  inclined  slightly  from  the  vertical.  They  are  generally 
used  for  lifting  heavy  weights  over  the  edge  of  a  cliff  or  wharf, 
in  which  case  only  rear  guys  are  used.  Weights  may  be  moved 
horizontally  by  manipulating  the  guys  so  as  to  change  the  inclina- 
tion of  the  shears.  They  may  readily  be  improvised  from  the 
trunks  of  trees,  etc.,  when  no  maneuvering  materiel  is  on  hand 
except  rope  and  tackle.  A  capstan  is  generally  used  in  connec- 
tion with  shears,  although  a  windlass  may  be  improvised  as  ex- 
plained later.  All  shears  are  constructed  on  the  same  principle. 

The  Spars  when  lashed  in  the  form  of  shears  are  called  the 
Legs. 


MECHANICAL    MANEUVERS  35 

The  upper  and  lower  ends  of  the  spars  are  respectively  called 
the  Head  and  the  Heel,  and  the  part  where  the  lashing  is  applied 
is  called  the  Cross.  Timbers  placed  under  the  heels  to  keep  them 
from  sinking  in  the  ground  are  called  Shoes.  The  heels  are  kept 
from  slipping  by  Heel  Lashings  which  are  hitched  to  Heel  Posts 
on  either  side  of  the  heels.  Heel  cleats  which  are  spiked  to  the 
.spars,  keep  the  lashing  from  slipping  up. 

The  Guys  are  usually  fastened  to  the  head  by  slings  into  which 
one  of  the  blocks  of  the  guy  tackle  is  hooked.  When  no  guy 
tackles  are  used,  a  bowline  in  the  end  of  the  guy  serves  the  same 
purpose.  The  upper  block  of  the  pain  tackle  is  hooked  into  the 
ends  of  a  sling  laid  between  the  spars  above  the  cross.  A  snatch 
block  hooked  into  a  short  sling  laid  around  one  of  the  spars  under 
the  heel  cleat,  serves  to  change  the  direction  of  the  fall  when  it 
is  run  back  to  the  capstan. 

The  stores  necessary  to  equip  a  pair  of  shears  are : 
Guy  Tackles — Two  single  blocks,  two  double  blocks. 
Main  Tackle — One   double  block,  one  treble   block,   and  one 
snatch  block. 

Cordage — Main  tackle  fall,  100  fathoms  3  to  5  inch  manila 
.rope;  guys,  50  fathoms  3  to  6  inch  manila  rope;  head  lashing, 
10  fathoms  3  to  4  inch  manila  rope;  heel  lashing  (two  each),  10 
fathoms  3  to  4  inch  manila  rope ;  contingencies,  50  fathoms  3  to  4 
inch  manila  rope. 

Straps — Main  tackle,  one  fathom  6-inch  manila  rope;  snatch 
block,  one  fathom  4-inch  manila  rope;  holdfasts  (six),  each  made 
of  one  fathom  4-inch  manila  rope;  Contingencies  (six),  each  made 
of  a  half  fathom  of  4-inch  manila  rope.  Spun-yarn  for  mousing, 
stops,  etc.,  one  ball  of  100  fathoms. 

Two  Cleats  for  heels,  to  prevent  the  lashing  from  slipping 
up,  made  by  cutting  lengthwise,  diagonally,  a  piece  of  6  by  G 
scantling  2  feet  long.  These  cleats  are  spiked  to  the  heels  6  inches 
from  the  bottom.  Twelve  stakes  for  holdfasts  for  guys,  6  feet  by 
G  inches;  four  stakes  for  heel  posts;  two  shoes  for  heels,  6-irieh 
plank,  1  foot  by  4  feet. 

To  Rig  the  Shears,  lay  the  ends  of  the  spars  on  a  trestle  abou+ 
three  feet  high,  the  right  leg  above  the  left,  so  that  they  cross,  at 
about  twice  their  thickness  from  the  ends,  with  the  heel  in  their 
proper  position. 

Pass  the  head  lashing  as  follows:  Take  a  good  piece  of  3^ 
or  4  inch  rope,  well  stretched,  middle  it,  and  make  fast  to  the 
shear  leg,  below  the  cross;  with  one  pass  the  requisite  number 
of  figure-of-eight  turns  around  both  spars,  heaving  each  turn  well 


MECHANICAL    MANEUVERS 

taut,  and  hitch  the  end  of  the  upper  part  of  the  shear  leg;  with 
the  other  end  pass  riding  turns  around  both  legs,  filling  up  the 
intervals  between  the  first  turns,  come  up  with  the  hitch  of  the 
first  end,  and  pass  f rapping  turns  around  all  parts  of  the  lashing 
between  the  shears,  finish  with  a  square  knot,  and  stop  the  ends 
back  with  a  good  spun-yarn  stop.  If  necessary  tighten  up  with 
wedges. 

It  may  be  done  in  another  way  as  follows :  The  two  spars  for 
the  shears  are  laid  alongside  of  each  other  with  their  butts  on  the 
ground,  the  joints  below  where  the  lashing  is  to  be,  resting  on 
a  skid.  A  clove  hitch  is  made  round  one  spar  and  the  lashing 
taken  loosely  eight  or  nine  times  about  the  two  spars  above  the 
hitch,  without  riding.  A  couple  of  frapping  turns  are  then  taken 
between  the  spars  and  the  lashing  is  finished  off  with  a  clove 
hitch  above  the  truns. 


Figure  18.     Shear  Lashing 

If  Guy  Straps  are  used,  they  can  be  put  on  doubled  as  follows : 
Middle  the  strap,  for  the  back  guys,  which  should  be  about  the 
same  size  as  that  mentioned  above  and  about  15  feet  long  when 
doubled,  having  the  splice  at  the  side,  so  that  it  cannot  enter  into 
either  bight;  lay  the  middle  between  the  spars  above  the  cross. 
Each  end  is  then  led  in  opposite  directions,  around  the  spar 
farthest  away  from  the  guy  for  which  it  is  intended,  and  the  ends 
brought  back  around  both  spars  crossed  ready  for  the  guy  blocks 
to  be  hooked  into  and  moused.  The  strap  for  the  fore  guy  is  put 
on,  doubled  in  the  same  manner  around  the  end  of  the  spars,  and 
thus  tMp strain  of  either  and  all  guys  tends  to  bind  the  spars 
togetheil 

If  the  straps  are  used  singly,  they  can  readily  be  put  on  by 
raising  the  heels  or  butts  and  slipping  them  up  the-  spars,  each 
strap  on  that  spar  farthest  away  from  the  guy  for  which  it  is 
intended,  the  straps  crossing  in  the  crotch  and  led  to  the  blocks. 


MECHANICAL    MANEUVERS  37 

If  straps  for  the  back  and  fore  guys  are  not  used,  the  back 
guy  is  arranged  as  follows :  The  back  guy,  a  good  manila  rope  of 
-3  to  6  inches,  depending  upon  the  weight  to  be  raised,  and  of  con- 
venient length  to  50  fathoms,  is  middle,  and  the  middle  placed 
above  the  cross,  the  left-hand  end  leading  downward,  bring  the 
left-hand  end  up  around  the  end  of  the  right  leg,  then  between 
the  legs  and  around  the  head  of  the  left  leg,  and  carry  it  over 
to  the  left  side  of  both  legs ;  carry  the  right-hand  end  around  the 
left  leg,  under  the  right  leg,  up  the  left  side  of  both  legs  and  across 
the  left-hand  end,  seize  the  crossing  with  spun-yarn,  the  ends 
of  the  guys  leading  to  the  blocks  opposite  the  sides  of  the  cross 
from  which  they  come. 

In  the  case  of  a  single  back-guy,  particular  care  must  be  taken 
to  bring  the  axis  of  the  shears  in  the  vertical  plane  containing  the 
holdfast  and  the  center  of  gravity  of  the  weight  to  be  lifted. 

The  Main  Tackle  Strap  or  Sling,  when  these  back  and  fore 
guys  are  used,  is  put  on  over  the  cross,  passing  over  the  whole  of 
the  straps,  except  the  bights  of  the  back  and  fohre  guy  straps. 

The  main  tackle  strap  is  put  on  as  follows:  Place  the  middle 
of  the  strap  doubled,  which  for  the  heavier  purposes  is  a  six  inch 
Manila  rope  of  sufficient  length,  under  the  cross  above  the  fore 
bring  the  ends  up  over  the  cross  above  the  fore  guy,  then  down 
underneath;  hook  the  upper  block  to  them  under  the  cross  below 
the  fore  guy  and  mouse  the  hook,  taking  care  that  the  splice  or  knot 
does  not  come  in  the  middle  of  the  strap  and  that  the  fall  leads  to 
the  rear.  Or  the  main  tackle  strap,  if  used  singly,  can  be  put  on 
by  raising  the  heel  or  butt  and  slipping  it  up  one  of  the  spars, 
and  putting  it  in  the  cross  over  the  head  lashings  and  other  straps ; 
its  bight,  \\hich  should  be  fitted  with  a  thimble,  should  hang  low 
enough  to  enable  the  upper  block  of  the  main  tackle  to  swing 
clear  between  the  spars  when  raised.  Should  it  be  required  to 
shorten  it,  one  or  more  turns  are  taken  with  the  strap  around 
the  head  of  the  spars. 

Two  cleats  are  spiked  to  the  heels,  6  inches  from  the  ends.  Lay 
the  shoes  under  the  heels.  The  shoes  should  be  on  the  same  level, 
and  in  bad  ground,  prevented  from  sinking  or  slipping  by  placing 
planks,  brush-wood  or  other  materiel  underneath,  securing  them 
by  pickets.  Drive  the  heel  posts  or  stakes,  two  for  the  lighter 
weights,  one  on  each  side  of  each  leg,  about  a  foot  toward  the 
head,  and  one  foot  outside;  make  a  timber  hitch  around  the  inner 
posts  with  the  heel  lashings,  pass  three  turns  around  the  leg  below 
the  cleats,  and  hitch  the  lashings  to  the  outer  posts.  For  the 
heavier  weights  four  pickets  should  be  driven  for  each  heel,  one 


38  MECHANICAL    MANEUVERS 

at  each  angle  and  outside  of  the  shoes,  a  clove  hitch  is  made  with 
the  center  of  the  ropes  around  each  foot  below  the  cleats,  arid  the 
ends  led  to  opposite  holdfasts.  As  many  turns  are  taken 
around  the  heel  posts  as  may  be  necessary,  the  running  ends  being 
brought  below  to  prevent  their  jamming  as  the  shears  rise. 

Drive  four  holdfasts  for  each  back-guide  as  fallows:  Two  on 
each  side,  three  feet  apart  in  a  line  of  the  legs  prolonged,  at  a 
distance  from  the  heels  twice  the  length  of  the  spars  from  the 
heels  to  the  crotch,  and  two  more  stakes  six  feet  in  rear  of  these. 

Lay  the  bight  of  a  strap  for  holdfasts  over  the  front  stake; 
connect  each  pair  of  front  and  rear  stakes  with  a  strap  twisted 
up  taut  to  insure  the  strain  being  distributed  over  all  the  stakes; 
drive  two  stakes  for  holdfasts  for  the  first  guy,  one  in  rear  of  the 
other,  in  the  prolongation  of  the  axis  of  the  shears  at  a  distance 
from  the  heel  twice  the  length  of  the  spars  from  the  heels  to  the 
crutch.  The  length  of  the  guys  should  >be  about  four  times  this 
distance. 

Hook  the  upper  block  in  the  end  guy  tackle  to  the  bight  of  the 
strap,  and  the  other  block  to  the  holdfast  strap,  which  is  over 
the  front  stakes;  mouse  all  hooks.  If  stakes  are  not  driven  for 
holdfasts,  any  convenient  hold  can  be  taken  around  a  tree,  gun 
or  pintle. 

Ordinarily  the  fore  guy  can  be  worked  without  a  tackle,  belay- 
ing it  over  the  holdfasts,  first  taking  a  round  turn  over  the  one 
next  the  shears. 

If  not  too  heavy,  the  shears  may  be  raised  by  lifting  the  head 
and  hauling  on  the  guy  tackles,  slacking  the  heel  lashings  as 
required,  and  tending  the  fore  guy  carefully  to  prevent  the  shears 
falling  over  toward  the  rear. 

When  raised,  hook  the  snatch  block  to  a  strap  placed  below  the 
cleat  on  the  leg  on  that  side  from  which  the  fall  leads, 
placing  the  block  as  low  as  possible,  so  that  the  fall  will  lead  hori- 
zontally to  the  drum  of  the  capstan. 

If  the  shears  are  too  heavy  to  raise  in  this  way,  bring  both 
guys  together  at  the  heels;  form  a  crutch  by  lashing  together  two 
poles  (or  use  the  legs  of  the  garrison  gin)  ;  place  the  guys  in  this 
crutch;  pass  the  end  of  a  small  rope  over  both  guys,  in  front  of 
the  crutch,  down  under  the  lashing,  and  take  a  rolling  hitch  with 
it  around  one  of  the  guys  in  rear  of  the  crutch ;  haul  the  rope  well 
taut,  and  secure  it  to  the  lower  end  of  the  crutch  leg. 

Raise  the  crutch  with  an  inclination  of  one-sixth  to  the  front, 
and  heave  up  the  shears  by  the  guy  tackles.  When  the  crutch 
ceases  to  act,  slack  it  to  the  ground  by  the  small  rope. 


MECHANICAL    MANEUVERS  39 

In  general  the  inclination  or  rather  rake  of  the  shears  should 
not  exceed  twenty  (20)  degrees,  or  four-elevenths  of  their  height, 
and  each  leg  should  have  about  one-half  of  this  inclination.  In 
this  position  the  strain  on  the  guys  will  never  exceed  one-half 
the  weight. 

The  shears  are  lowered  by  slacking  the  guys  and  heel  ropes, 
or  by  small  shears  or  lever. 

The  following  diagram  will  serve  as  a  guide  in  placing  shears, 
holdfasts,  etc. : 


Figure  19 

AD  and  BC  are  the  legs  of  the  shears. 

F,  the  front  guy  holdfast. 

G,  the  rear  holdfast. 

E,  the  center  of  the  line  AB,  at  right  angles  to  FG. 

AD  =  BC 

The  splay ,AB  =  1/3  CE. 

FF  and  EG  =  at  least  2  AC. 

The  lashing  to  be  twice  the  thickness  of  the  spars  from  the 
ends.  When  two  fore  or  two  rear  guys  are  used,  the  holdfasts 
should  lie  in  prolongation  of  the  legs,  at  a  distance  equal  to  EG 
and  EF. 

When  the  locality  will  not  admit  of  rigging  the  shears  in 
position  as  described,  they  may  be  raised  from  the  foot  of  the 
wall  or  cliff  by  means  of  a  gin  or  lighter  shears  in  the  following 
manner:  Pass  the  shear  lashing  and  attach  the  front  guy;  lash  a 
stout  spar  across  the  legs  about  two  feet  above  the  center  of 
gravity,  giving  the  heels  the  proper  -spread;  fasten  a  small  rope 
to  each  heel  to  serve  as  guys ;  hook  the  gun  tackle  to  a  strap  firmly 
attached  to  the  middle  of  the  cross-spar,  and  heave  away,  tending 
the  guys  carefully.  As  the  head  of  the  shears  comes  above  the 
crest  of  the  wall,  put  on  the  back  guys  and  main-tackle  strap 
and  hook  on  the  tackle;  mouse  all  hooks;  raise  the  shears,  place 
the  heels  on  the  shoes,  pass  the  heel  lashings,  set  up  the  guys,  and 
lower  the  gin  to  the  ground,  leaving  the  spar  in  position. 

When  no  capstan  is  availible,  a  windlass  may  be  improvised 
as  follows :  Nail  a  strong  cleat  on  the  upper  side  of  each  leg  and 
about  two  feet  from  the  heel,  the  butt,  or  square  end  of  the  cleat 


40  MECHANICAL    MANEUVERS 

down;  lay  a  round  spar  a  little  more  than  one-third  the  length  of 
the  shears  across  the  legs,  one  foot  above  the  butt  of  the  cleats; 
pass  loosely  two  strong  lashings  (3-inch  rope)  around  this  spar 
near  the  ends  or  near  where  it  rests  on  the  legs ;  f rap  the  lashings 
near  the  spars)  and  tie  the  ends.  The  lashing  should  be  loose 
enough  after  frapping  to  leave  loops  to  pass  over  and  under  the 
butts  of  the  cleats,  taking  care  to  have  them  of  equal  length.  Grease 
the  spar  and  legs  where  they  are  in  contact,  and  the  spar  under 
the  lashing.  Pass  two  or  more  straps  of  \.l/2  or  2  inch  rope  doubled 
around  the  end  and  middle  of  the  spar,  put  one  end  through  the 
bight  of  the  other  and  take  a  turn  around  the  spar.  Put  a  hand- 
spike the  free  bight .  to  be  used  as  a  lever  to  turn  the  windlass. 

These  straps  should  be  nailed  to  the  spar  to  prevent  slipping. 

The  windlass  is  chocked  by  allowing  two  or  more  handspikes 
to  touch  the  ground  on  the  opposite  side  of  the  windlass. 

Light  guns  may  be  passed  over  ditches  or  from  different  places 
practically  at  the  same  level,  but  too  far  apart  for  one  pair  of 
shears  to  be  used,  by  means  of  two  pairs  of  shears  as  follows : 

Big  two  shears  as  described  above,  one  on  either  side  of  the 
ditch,  except  that  the  back  guy  is  necessary  for  each. 

The  shears,  when  raised,  should  be  nearly  vertical,  only  inclined 
slightly  toward  each  other,  for  the  strain  is  sometimes  excessive 
on  the  guys. 

Before  raising  the  shears,  connect  the  heads  by  a  gun  tackle 
purchase,  the  fall  which  is  slacked  off  as  the  shears  rise,  leading 
to  either  side  as  desired. 

The  back  guys,  and  the  two  main  tackles  for  the  gun  or  weights 
mentioned,  should  be  luff-tackle  purchases. 

Straps  or  suitably  sized  ropes  should  be  used  and  adjusted 
over  the  heads  of  the  shears,  as  described  before  for  the  back  guys 
and  for  the  gun  tackle  purchase  for  connecting  the  shear  heads. 
After  the  shears  are  raised  and  guys  well  secured,  both  main 
tackles  are  hooked  into  straps,  passed  around  the  gun  and 
trunnions,  and  the  hooks  moused. 

The  gun  is  passed  across  by  hauling  on  one  tackle  and  at  the 
same  time  slacking  off  the  other. 

Both  falls  can  be  led  to  the  same  side  of  the  ditch,  if  desired, 
but  to  different  capstans. 

When  the  garrison  or  casemate  gin  is  used  as  shears  the 
prypole  is  replaced  by  a  parting  block  of  the  same  diameter. 

The  guys  are  attached  as  follows :  Middle  the  rope  for  the  back 
guys;  push  the  bight  through  the  clevis  from  below  and  slip  it 
around  both  legs ;  haul  the  ends  back  tight  and  lay  them  over  the 


MECHANICAL    MANEUVERS  41 

head  of  the  gin  to  the  rear,  each  part  lying  bet\v*een  the  nearest 
leg  and  the  parting  block,  taking  care  to  place  canvas  under  the 
ropes  to  prevent  chaffing. 

The  fore  guy  is  hitched  around  the  clevis  belt. 

A  single  back  guy  may  be  used,  formed  of  a  tackle  of  the  same 
size  as  the  gin  tackle,  hooked  into  a  strap  applied  as  described 
for  the  guy  ropes.  In  this  case  particular  care  must  be  taken  to 
bring  the  axis  of  the  shears  in  the  vertical  plane  containing  the 
holdfast  and  the  center  of  gravity  of  the  weight  to  be  lifted. 

A  Gin  Pole  is  a  single  spar  raised  and  operated  in  the  same 
manner  as  shears.  It  is  generally  fitted  with  four  guys,  the 
fore  guys  extending  at  an  angle  of  45°  from  the  line  of  the  front, 
the  rear  guys  at  an  angle  of  45°  from  the  line  of  the  rear.  A  cleat 
is  spiked  to  each  side  of  the  spar  near  the  head  to  keep  the  guy 
straps  and  main  tackle  sling  from  slipping  down.  A  turn  or  two 
is  taken  around  the  spar  with  the  guy  straps  doubled,  letting  the 
ends  come  clear  to  allow  a  guy  tackle  block  to  be  hooked  into  each. 
The  main  tackle  sling  is  put  on  in  the  same  way,  the  upper  block 
being  hooked  into  both  ends.  A  heel  cleat  is  spiked  to  each  side 
of  the  spar  and  the  heel  lashings,  heel  posts,  and  shoes  are  used 
as  for  the  shears. 

Approximate  Size  and  Length  of  Spars  Required  for  Shears. 

Weight  to  be  raised  Mean  Diameter  Length 

2  tons  7  to     9  inches  20—30  feet 

3  to     5  tons  11  to  13  inches  30 — 40  feet 

5  to  12  tons  13  to  16  inches  40—50  feet 

12  to  25  tons  16  to  24  inches  50—60  feet 

For  a  gin  pole  a  spar  approximately  1/3  great  mean  diameter 
than  given  above  should  be  used. 

HOLDFASTS 

To  prepare  a  fastening  in  the  ground  for  the  attachment  of 
guys  or  purchases,  stout  pickets  are  driven  into  the  ground,  one 
behind  the  other  in  line  of  pull.  The  head  of  each  picket  except 
the  last  is  secured"  by  a  lashing  to  the  foot  of  the  picket  next 
behind.  The  lashings  are  tightened  by  rack  sticks,  the  points 
of  which  are  driven  into  the  ground  to  hold  them  in  position. 
The  distance  between  the  stakes  should  be  several  times  the  height 
of  the  stake  above  the  ground. 

Another  form  requiring  more  labor  but  having  much  greater 
strength  is  called  a  Deadman,  and  consists  of  a  log  laid  in  a 
transverse  trench  with  an  inclined  trench  intersecting  it  at  its 


42  MECHANICAL    MANEUVERS 

middle  point.  The  rope  is  passed  down  the  inclined  trench,  takes 
several  turns  around  the  log  and  is  fastened  to  it  by  half  hitches 
and  marline  stoppings.  If  the  cable  is  to  lead  horizontally  or 
inclined  downward  it  should  pass  over  a  log  at  the  outlet  of  the 
inclined  trench.  If  the  cable  is  to  lead  upward  this  is  not  neces- 
sary, but  the  anchor  log  must  be  buried  deeper. 


TO     »t. 


Y. 
m.m  21,1908 


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